Research On Inertia Evaluation Method Of High Proportion New Energy Power System

With the increasing proportion of new energy in China ’s power grid,the inertia level of the power system continues to decrease,which poses a serious threat to the system frequency security.Inertia plays a key role in the frequency security and stability of power system.Low inertia will lead to the decrease of system antidisturbance ability.In order to clarify the inertia level of the system and guide the rational allocation of the inertia lifting device,this thesis focuses on the inertia evaluation of the high-proportion new energy power system.The inertia of high proportion of new energy power system is analyzed,and the inertia evaluation method of different levels of new energy power system and the minimum inertia evaluation of system considering dynamic frequency stability constraints are proposed.The main research contents are as follows :Firstly,the inertia characteristics and supporting capacity of high proportion new energy power system are studied.The essence of power system inertia is expounded,and the source of power system inertia is summarized.The inertia characteristics and inertia response of new energy power generation system and synchronous unit are analyzed,and then the inertia support ability of synchronous unit and new energy unit is compared and analyzed.The above research content lays a theoretical foundation for the subsequent power system inertia evaluation.Secondly,the regional inertia evaluation of new energy power system is studied.Aiming at the spatial and temporal distribution characteristics of high proportion of new energy access,combined with cluster analysis,the system is divided into regions,and a regional inertia evaluation method based on kinetic energy theorem is proposed.The electrical distance and inertia distribution characteristics of the system are considered to provide a basis for the division of the system area.The core unit selection index of each region is defined as the evaluation data acquisition point,and the regional inertia level of the system is evaluated by combining the kinetic energy theorem.The simulation results show that the proposed method has high evaluation accuracy and small data sample dependence.Then,the node inertia evaluation of new energy power system is studied.In order to accurately locate the weak nodes of system inertia and perceive the spatial distribution of system inertia,a node inertia evaluation method based on inertia center theory is proposed.The inertia evaluation index of the system node is established,and the inertia center frequency of each region is calculated.For the new energy access area,the equivalent inertia constant of the new energy unit is calculated by parameter identification method.The evaluation results of node inertia of power system before and after new energy access are analyzed respectively.The simulation results show that this method improves the accuracy of node inertia evaluation and can characterize the impact of new energy access on node inertia level.Finally,the minimum inertia demand assessment of the system under dynamic frequency stability constraints is studied.Aiming at the frequency stability problem caused by the decrease of inertia after large-scale new energy access to the system,the minimum inertia required by the system is evaluated considering the system frequency constraints.According to the kinetic energy of the system,an index for judging the frequency stability of the system is proposed,and the reference value of the inertia lifting device is obtained.The minimum inertia evaluation of the standard system and the actual equivalent system in a certain area is carried out respectively.The simulation results show that the method can adapt to the power system with different proportion of new energy access,and its minimum inertia evaluation value can provide a basis for new energy consumption and system frequency stability analysis.