Research On Inertia Characteristic Analysis Methods Of New Energy Power System

The generation of new energy sources such as wind energy and solar energy is conducive to reducing the consumption of primary energy by the power system.this is one of the important means to deal with global energy and environmental problems.However,the absorption of large-scale new energy makes the frequency characteristics of the power grid more complicated.Inertia,as an important characteristic parameter that determines the dynamic behavior of the frequency after the power grid is disturbed,has a complex and diverse manifestation in the new energy power system.Therefore,there is an urgent need to study a comprehensive evaluation method system for the inertia characteristics of the power grid,and analyze the dynamic characteristics of the inertia of the new energy power system.In this paper,the inertia characteristics of new energy power system are taken as the research object,and the analysis and evaluation methods are studied,and some results are obtained.The main research contents are as follows:Firstly,in view of the problem of inertia characteristics change of modern power system in the case of large-scale new energy grid connection,the basic definition related to grid inertia is introduced in detail,and different forms of inertia characteristics in new energy power system are analyzed.Combined with the frequency instability process of large-scale power system blackouts in recent years,the problem of reducing the system moment of inertia caused by the large-scale consumption of new energy in power grid is studied.Furthermore,the influence of inertia reduction of modern power system on power grid frequency stability is analyzed,which shows the practical significance of establishing inertia characteristic evaluation system of new energy power system.Secondly,according to the characteristics of complex inertia characteristics of modern new energy power system,a method of power grid inertia characteristics evaluation based on the theory of inertia center is proposed.This method extends the concept of the moment of inertia of synchronous generator to the whole system and the buses.It can evaluate the moment of inertia characteristics of generation equipment,buses and the whole system in the new energy power system,and realize multi-level and all-round identification of the dynamic moment of inertia characteristics of power grid.The validity of the proposed method is verified on the 3-machine 9-bus system and IEEE 39 bus test system,and the relationship between the inertia time constant of the generator,the line reactance,the topological structure and the inertia of buses is calculated and analyzed.Then,for the large-scale power system with complex grid structure and wide cross region,the identification method of grid inertia distribution based on the propagation characteristics of electromechanical is proposed.Based on the distribution characteristics of the propagation velocity of electromechanical wave in the power grid,the method reveals the inertia difference in each region of the power grid by using the mapping relationship between the wave velocity and the inertia.It can quantitatively evaluate the inertia level in each region of the power grid under different operation conditions.Based on the IEEE 39 bus system and the multi terminal DC transmission system,the inertia distribution of the grid before and after the wind farm is visualized,and the influence of the inertia of the new energy merging buses on the frequency stability of the grid is compared and analyzed.The simulation results show that the proposed method can directly reflect the change of inertia of each region before and after the new energy grid connection.It can provide effective reference for the selection of new energy grid connection points in the power grid planning stage.Finally,the practicability of two methods is verified in the real power grid.Based on the measurement data of PMU in Hunan power grid,the evaluation of inertia distribution of largescale real system is realized.Further,based on the identification results of the inertia distribution of the actual power grid,the inertia response and frequency support capability of the disturbed power grid areas are analyzed.The frequency stability analysis results of the power grid areas are verified by using the actual frequency fluctuation of the power grid short circuit fault.