The Study On Static Voltage Stability Based On The Characteristic Structure Analysis

Microgrid is widely used,which as a new type to absorb new energy of grid,however,in the operation process of the microgrid,because of the uncertainty of micro source and load of uncontrollability will cause voltage fluctuations,and even the voltage stability problem,so this thesis study on the static voltage stability problem for the microgrid has theoretical significance and application value.Taking ac microgrid as the research object,the mechanism of static voltage stability of micro grid is analyzed in depth from the aspects of photovoltaic power generation characteristics and wind power generation characteristics,working characteristics of battery and uncontrollability of load,and the influencing factors of static voltage stability in micro grid are given.Whether the micro-source is controllable or not is classified,for the uncontrollable micro source combined with its operation pattern,the corresponding PQ control or constant voltage constant frequency control is adopted;while for the controllable micro source combined with the microgrid of impedance characteristics,the anti-droop control is adopted.Based on the traditional power flow jacobian matrix,combining the characteristics of micro-source randomness and volatility in the microgrid and the control strategies of various micro-source inverters,and taking the static voltage characteristics of load into account,the corresponding improved power flow model is established.Based on the model,the characteristics of the structure analysis method was applied to the static voltage stability problem of micro grid,then node voltage participation factor obtained and combining the generalized Tellegen theorem obtained voltage relative sensitivity can together quickly judge the weak area of the system and the key branch and micro source,the minimum modulus eigenvalue can be geted through the characteristics structure analysis,its influence of the key source and branch in the weak area is verified.In Matlab simulation analysis,the simulation verifies that the stability of voltage in the microgrid system is mainly related to active power ccording to the characteristics of the microgrid system impedance ratio.The relative sensitivity?U?Pand node voltage participation factor p_ki of the microgrid example proposed in this thesis are compared,then the weak area of the microgrid and voltage instability is determined.Finally,the influence of the changes about key branches and micro-source in the weak area on the voltage stability of the system is analyzed to verify the effectiveness of this method.