Study On Evaluation Method Of Power Exchange Ability Of Extra-High Voltage Power Grid

During the period of the China12th5-year Plan, it has large transmission capacity and long transmission distance that the UHV AC and DC transmission channel of ’3-Hua’ power grid. In case of that the faults happens on UHV transmission line or interval exchange power capacity between regional grids changes greatly within a short period of time, it will cause huge impact on power exchange channel, lead to transient unstable of phase angle or frequency, threatens the security and stability operation of power system. Therefore, it becomes the concerned focus of the present power system that the researching on the evaluating method of AC exchange capacity between regional network under influence of various factors.Based on extensive reading on literature and articles, It is deeply researched in this paper that the influence factors, evaluation index and method combined with the EHV power grid exchange capacity. The main research contents are as follows:Firstly, it is put forward that the evaluation index of frequency stability based on prediction and calculation method of frequency stability characteristic. The exchanging power capacity limit is calculated with the verification of steady frequency stability under the condition of changed exchange power capacity. At the same time, it is also put forward that the evaluation index of calculation on active power-voltage sensitivity. The exchanging power capacity limit is calculated with the verification of steady voltage stability under the condition of changed exchange power capacity. The index and method are proved correct and effective by the simulation and calculation on example of2012"3-Hua" power grid model.Secondly, it is put forward that the effectively equivalent model and equivalent transient energy function based on the study of traditional transient energy function and stability area analysis. The exchanging power capacity limit is calculated with the verification of equivalent transient energy function under the condition of changed exchange power capacity. The index and method are proved correct and effective by the simulation and calculation on example of2012"3-Hua" power grid model. Thirdly, it is put forward that the evaluation index of effect between AC and DC transmission system based on the theory of optional flow constraints. The exchanging power capacity limit is calculated with the verification of fault on DC transmission line under the condition of changed exchange power capacity. The index and method are proved correct and effective by the simulation and calculation on example of2015"3-Hua" planning model.Next, it is calculated that the exchanging power capacity limit by the former verification on the2012basic mode,2012strengthen mode and2015mode of the "3-Hua" power grid, and it is also analyzed that the influence factors on exchange capacity limit. It is mentioned that the backup ratio index of steady state, transient state and DC transmission line. It is analyzed that the variation tendency alone with the changing of power grid structure. Then it is put forward that the reasonable range of power exchange capacity on "3-Hua" planning power grid model.Finally, it is summarized that the main work and innovation points of this paper, and it is put forward that the expectation of following work.