| with the development of new energy power generation technology at home and abroad,parts of new energy power generation have accounted for more than 50% of the total generating capacity of local chongming island of China’s new energy utilization rate reached 100%.Even most of the new energy by inverter connected to the power system,inverter compared with synchronous generator with low inertia,damping characteristics such as low.When new energy reaches a certain proportion of permeability,the system will have the characteristics of the inverter,low damping,low inertia characteristics make its robustness,especially to the frequency of the supporting capacity significantly lower;Under the environment of the external disturbance,the system response speed too fast,the frequency fluctuation is bigger,intermittent and randomness of new energy at the same time,increased the possibility of a disturbance,this will pose a threat to the system frequency stability.Modern unit has the ability of flexible change inertia,by introducing virtual synchronous control technology makes the problem remission,enhance the system robustness,but still lack of quantitative characterization,inertia effect the performance of the stability evaluation system.This paper firstly establishes a second-order mathematical model of power system with virtual inertia parameters under small disturbances.Generally,second-order model is used in the planning process of power system.Since the inertia link only affects the mechanical part of the power system,the second-order model can be used to explore its impact on the power system.Based on the model,the frequency stability of the system is quantitatively characterized by the two-norm lyapunov direct method,and the stability degree of the system is analyzed from the perspective of wave energy.In different structure to explore the system structure and the influence of the inertia coefficient on the system frequency stability,using three area interconnected power system simulation and analysis of various regions under different inertia coefficient oscillation characteristics of net and chain structure,at the same time two norm to make use of the lyapunov direct method under different inertia parameters of two kinds of structure model of evaluate the dynamic stability of low frequency oscillation occurs,get different oscillation characteristics of the structure,the simulation results reveal the ring network,the virtual moment of inertia can play a role,in every area of inertia changes presents the characteristics of the overall smooth transition.To improve the efficiency of inertia optimization calculation to find suitable calculation optimization method,the main use of various kinds of intelligent algorithm to solve the optimization problem,the traditional value type intelligent algorithm such as genetic and particle swarm algorithm is easily plunged into local optimum,the defects of numerical methods to solve the problems and explore new areas of algorithm,is put forward using a gravity interpolation optimization method based on voronoi diagram,the method is automatic segmentation of voronoi diagram function,divided the new node classification,the optimal node set respectively is tentative,transition node,effective area.At the same time,the above three nodes are taken as new sample points.At this time,the barycentric interpolation method can be used to estimate the solution of non-sample points according to the value of sample nodes,and the unknown node can be estimated more accurately under the condition of fewer sample points.The hybrid method also has the advantages of fast convergence,high accuracy of results,automatic adjustment of the search range,and not easy to fall into the local optimal solution.At the same time,it provides an effective way for the inertia planning problem which may appear in the future. |
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