Research On On-Line Static Security Analysis And Assistant Decision-Making Method For UHV AC/DC Grid

Electric power is the foundation of a country's industrial development,the lifeline of national economic development,the basic guarantee for the national economy and people's livelihood.Power security is directly related to the healthy development of the national economy and the long-term stability of society.With the continuous expansion of the power system,the power system gradually develops toward large units,large power grid,high voltage and long-distance power transmission,the static safety of power systems is becoming increasingly prominent.Analysis of the static safety issues of the power system helps to improve the safe and stable operation of the power grid.Therefore,how to improve the calculation speed of static security analysis,propose measures to solve static security problems,and ensure fast and real-time stable operation is necessary.The thesis studies the applicability and limitations of DC power flow method,compensation method and sensitivity analysis method in the actual analysis.In order to adapt to the development and security requirements of the power grid,the traditional fast static security analysis algorithm is improved based on the partial factorization method using the factor table additional chain technology.The improved fast static security analysis algorithm can adapt to the breaking,adding and parameter modification processing of various types of components,achieving a combination of rapidity and accuracy.Through the comprehensive analysis of a large number of actual security control device strategies,the key elements such as the organization form of security control strategy,basic control logic,and control quantity allocation are analyzed,and the fine control model of security control strategy is carried out.The calculation of the corresponding security control strategy is automatically matched according to the change of the fault during the static security analysis calculation process.For the branch or section that exceeds the current flow caused by the expected fault,the static safety assisted decision calculation method for the single fault is studied,and the sensitivity of each component that can participate in the adjustment to the over-limit component in this state is calculated.Sensitivity analysis was performed without changing the power balance of the entire system.Sensitivity analysis was performed without changing the power balance of the entire system.The adjustment process aims at the minimum control cost.According to the upper and lower limits of the output of the generator set and the thermal stability limit of the branch,the final adjustment strategy for eliminating the thermal stability limit is given.When multiple devices exceed the limit in the system,the auxiliary decision that only considers the single device thermal stability caused by a single fault cannot give the case of eliminating multiple devices at the same time.Therefore,for the multi-fault problem in the decision-making process,a multi-fault coordination assistant decision-making method based on adjustable adequacy is studied.For the conflict situation that the other equipment exceeds the limit due to the adjustment of the over-limit caused by the breaking fault of a certain component,according to the concept of the adjustable margin,the sensitivity of the adjustable device to different faults is calculated according to the principle of minimum adjustment.Solve the optimal adjustment scheme.Finally,based on the above control strategy method,multiple fault simulations are applied to the actual grid calculation and analysis,which can make the grid safe and stable after adjustment,and has a good application prospect.