Quantification And Control Of Voltage Stability Of Power System With Wind Power

Power system instability,especially voltage collapse,will lead to partial and even large-scale sustained load loss,which directly affects the reliability and economy of power system operation.The reactive power is closely related to the voltage stability and voltage collapse of the power system,which is of great significance to the stable operation of the power system.The influence of reactive power shortage on system reliability and the identification of weak points considering system failure have not been paid enough attention to.At the same time,with the utilization rate of clean energy wind power increasing year by year,due to the randomness and volatility of wind power,wind power grid connection will have a great impact on the power system,and further increase the possibility of system power fluctuation voltage instability.It is very important to optimize the reactive voltage control in the power system with wind power to ensure the economy and safety of the power system.The research contents of this paper mainly include:1)The Weibull distributed wind speed model with shape parameter 2 is selected,and the scene division of the doubly-fed induction fan is carried out based on the scene analysis method to solve the uncertainty of the fan output.Based on the control mechanism of reactive power voltage inside the doubly-fed induction fan,the limit of reactive power output of the doubly-fed induction fan is determined,and the doubly-fed induction is regarded as a reactive power source,which makes full use of the reactive power regulation ability of the doubly-fed induction fan.The mechanism of voltage stability is studied from the aspect of static stability.The static voltage stability analysis method and several commonly used static voltage stability indexes are introduced.2)The reactive power reserve capacity of the key nodes is an important index to measure the voltage stability of the system.In this paper,the weighted sum of reactive power reserve of each doubly-fed wind turbine is defined as the reactive power reserve margin of the system.In the process of reactive power compensation,each control variable has different sensitivity to the reactive power enhancement.In this paper,the sensitivity of the reactive power reserve of the doubly-fed wind turbine generator is calculated according to the sensitivity of each control variable,and the average sensitivity of each control variable is obtained.3)The linear correlation between reactive power reserve margin and voltage stability margin is established by multi-thread regression equation,and the multi-objective reactive power reserve optimization model is established to improve the static voltage stability margin of the system.4)Voltage and reactive power coordinated control model is essentially a multi-objective optimization problem in the field of power system.With the improvement of power system operation requirements,single-objective optimization can no longer meet the demand of power system.The optimal solution obtained by a single objective function will make other objectives unable to meet the requirements at the same time.The multi-objective optimization problem in electrical field can not be solved directly,which requires the analysis of the research object and the application of mathematical theory and method to transform the problem into a computable mathematical model.The traditional genetic algorithm is improved.In order to avoid falling into the local optimal solution,dynamic adaptive improvement is made in fitness function and crossover and mutation operation,which makes the algorithm not precocious and more suitable for solving multi-objective optimization problems.