Probabilistic Dynamic Continuous Power Flow Method For AC/DC Power System With Wind Power In Consideration Of Source And Load Frequency Characteristics

The scale of power system is expanding,the proportion of clean energy such as wind energy is increasing.The capacity and scale of direct current transmission are continuously breaking new high.The voltage stability control of AC-DC hybrid system is becoming more and more complicated.Load characteristics play an important role in voltage stability.The study of static voltage stability region of AC/DC system provides a new reference for operation control.Considering load static characteristics,wind power access and DC control mode,this paper studies the static voltage stability region of AC/DC system.Firstly,according to the static characteristic model of load voltage and frequency,the close relationship between load voltage and static voltage stability of power system is found.Based on the continuous power flow method,the probabilistic dynamic continuous power flow model of wind power AC and DC system with load static characteristics is established.The probabilistic treatment of wind power output is adopted.The unified iteration method is used to calculate AC/DC system power flow,and the detailed solution steps are given.The load margin expectation is calculated in 112 scenarios,such as AC/DC continuous power flow method,N-state system,N-1 system,single-dual wind field access,DC control mode,and so on.The effectiveness of this method in solving load margin is verified.Then,based on the proposed probabilistic dynamic continuous power flow model of AC/DC system,the approximate tangent plane equation of the stability region boundary of AC/DC system is derived,and the factors affecting the formation of the tangent plane are extracted to analyze the formation of the tangent plane more intuitively.The sensitivity analysis of the parameters affecting the tangent plane of the stability region,such as DC control mode,load static characteristics,wind power and load continuous parameter ?,is carried out.In order to explore the influence degree of each parameter on the formation of the stable domain tangent plane find out the law of the influence of each variable on voltage stability.It has certain reference value for the analysis of static voltage stability region.Finally,on the basis of tangent plane sensitivity analysis of stability region,combining reactive power-voltage sensitivity index and load margin index,a weak area evaluation index considering frequency fluctuation,load margin and reactive voltage sensitivity is constructed.A weak area evaluation method for DC receiving terminal AC nodes of AC/DC system is proposed,and verification analysis is carried out under different DC control modes.It provides a reference for weak area analysis of AC/DC system and a new idea for static voltage stability analysis of the system.In this paper,the static load characteristics,wind power access and DC control methods are studied in the static voltage stability region of AC/DC system.The influence degree of each factor on the static voltage stability domain tangent plane is analyzed.The indicator of weak area of AC/DC system provides reference value for reliable operation and scheduling of the system.