Research On Optimal Allocation Of Dynamic Reactive Compensation In AC/DC System

At present,researches on optimal allocation of dynamic reactive power compensation are all carried out under the background of AC power network,but the influence of HVDC transmission project joining was not considered.And most of the optimization methods obtain results from a certain perspective after linearization,or the target were just to optimize the installation site.Those methods are specific and one-sided.This paper focuses on the dynamic reactive power compensation to improve the stability of AC-DC system under large disturbance.Combined with the topological structure of the power network,the quasi-steady state characteristics of the AC-DC system and the transient information of the system,a multi-stage dynamic reactive power optimization method considering the characteristics of AC-DC power network is proposed in this paper.The Multi-stage method includes the assessment of correlation degree of node voltage stability,the severity of node voltage instability and the improved sensitivity index.Each stage is conducive to the analysis of the next stage,to finally obtain a better dynamic reactive power compensation configuration scheme.Based on the voltage-reactive power sensitivity analysis of AC-DC system and the HVDC operation characteristics,the correlation degree of node voltage stability is evaluated.And a partition method for reactive power compensation configuration considering the influence of DC power injects is proposed.Then,taking the improvement of the system voltage stability under large disturbance as the guide,and considering the failure of HVDC system commutation,the voltage variation in AC-DC power network is analyzed.The trajectory violation integral is used to describe the severity of node voltage instability.And a method to screen the serious fault sets which lead to voltage drop is presented.On those basics,a multi-objective optimization model for improving voltage stability and reducing econolic cost is established.Furthermore,the trajectory sensitivity index of voltage combined with the economic cost factor is proposed as the objective of the optimization problem.After improving the empire competition algorithn(ICA),an improx ed ICA algorithm-based optimization method is proposed for the optimization problem.The effectiveness of the optimization method is verified by calculation and simulation,which can provide a reference for the planning of dynamic reactive power compensation in AC-DC power network.