Research On Static Voltage Stability Online Risk Assessment And Preventive Control For Power System With High Proportion Of Wind Power

In recent years,new energy power generation especially wind power is growing rapidly.Its large-scale connecting to grid ease the increasingly tense energy situation and the traditional energy pollution to the environment in some extent.However,with the continuous improvement of the proportion of wind power,the fluctuation and randomness of the wind power output significantly poses a great threat to the static voltage stability of power system.It is an urgent problem to ensure the static voltage stability under large-scale wind power access to power system.In this paper,the influence of high proportion wind power grid on the static voltage operation of power system is evaluated from the perspective of risk,and the comprehensive risk index of static voltage stability margin in future winds is constructed under the predicted probability of wind power output.The risk control index is used to prevent and control the risk index,and the comprehensive control strategy is established,and the optimal control strategy is obtained by using the original dual interior point method.Firstly,the history of static voltage stability research is reviewed,and the characteristics of various static voltage stability analysis methods are briefly introduced.The shortcomings of various methods in the static voltage stability evaluation of wind power system are described.This paper also summarizes the research status of risk assessment and prevention and control in power system.Secondly,this paper introduces a new method for thevenin equivalent parameter identification based on wide area measurement.In this method,the load is equivalent to the form of impedance,and then the admittance matrix element is updated to generate node voltage equations,at last the equivalent parameters could be found by solving the equations.with gaussian elimination method.The proposed method has the advantages of high precision and fast calculation speed.It can quickly track the change of static voltage stability margin caused by wind power fluctuation.This method can be the cornerstone to build online risk index.Then,a risk index is proposed to evaluate the change of static voltage stability caused by wind power fluctuation,including probability information and severity.The probability information is the probability distribution of the the short-term prediction of wind power output which is forecasted using the Markov chain model based on the statistics of the historical wind power change information.The severity reflects the degree of static voltage stability,which is inversely proportional to the static voltage stability margin and is calculated from the results of thevenin equivalent parameters.The combination of the two parts can predict the static voltage stability risk information for short-term system operation,alerting the high-risk scene and providing decision support for the implementation of the preventive control measures.Finally;for the high risk index,the preventive control measures are taken,and the static voltage control framework of risk assessment and preventive control is constructed.The interior-point method is used to solve the preventive control model with the target of minimum regulation cost and risk security constraint.The simulation example verifies the validity of the proposed risk index and the preventive control model.