Analysis Of Power System Frequency Dynamic Including Wind Energy

Frequency is an important parameter of power system, it is an important index for the operation security monitoring and analysis of power system. Frequency stability depends on the balance of active power between generation and load fundamentally. In recent years, a number of large blackouts around the world are accompanied by frequency crashes. While, more and more renewable energy like wind connected to the grid by power electronic devices, reducing the inertia of the system, the impact of wind power’s intermittent, random fluctuations and serious climbing event frequency stability of the system is getting worse. Therefore, to study and predict the power system frequency dynamic after disturbance and the analysis for the influence of wind to frequency dynamic is necessary.This dissertation studies how to predict the power system frequency dynamic and analysis the influence of wind to frequency dynamic. Several achievements have been gained in this dissertation. The main content of research is as following:(1)Some basic concepts related to power system frequency and frequency characteristics are introduced, some index suitable for power system frequency dynamic security analysis and assessment are put forward:the extreme value, the mean and variance, the qualified ratio, high (low) frequency events, dynamic frequency events, the time and space characteristics of power frequency, etc. Measured data and simulation data of a regional power grid are used for frequency dynamic analysis and evaluation through the index before.(2)A method for power system frequency dynamic prediction after disturbance on v-SVR is put forward. To predict the dynamic frequency using this method is quick and accurate enough and it is of good generalization and popularization. Compared with the traditional method, this one can take a number of factors such as the size of spinning reserve and its mode of distribution, the limitation of generator’s maximum output, network, load and prime-turbine on the influence of the power system frequency dynamics into consideration. The proposed method is verified in the New England 10-machine 39-bus system and an actual grid of a province in our country.(3)A model for system frequency response analysis including wind generator has been proposed, then the method of wind generator for system frequency regulation has been accessed quantitatively.An analytic expression has been derived from the proposed model which based on the classical SFR and it can analysis the power system dynamic with wind generator quantitatively, and to verify the proposed model’s effectiveness on the test system. Then, we analysis the permeability of wind power, the virtual inertia parameters, the virtual damping parameters and its sensitivity of the lowest frequency and frequency variation using this model.