A New Method Of Electric Distance Calculation And Its Application In Reactive Power Partition

At present the economy of our country has been developed rapidly,the electric power industry has been entered the period of large units,large power grid and high voltage.With the expanding of power grid scale,the system structure is more complicated.Combined with the diversification of power generation and the backward of power system planning and increase of uncertainty factors caused voltage stability problems are becoming more and more outstanding.Power system reactive power/voltage control has been considered as the effective method to improve power transmission capacity and voltage stability of power system.Among them,the voltage hierarchical control is widely used.Voltage hierarchical control's premise is the reactive partition which is based on the electrical distance.And the traditional electric distance calculations is based on the sensitivity method.It transform the Jacobi matrix to the voltage/reactive power sensitivity and cluster the nodes represent the electric distance that comes from sensitivity matrix elements and form grid partition eventually.Due to the sensitivity of complex power system calculation only meet differentiability and does not meet the Cauchy-Riemann conditions.Therefore,the method of sensitivity is not analytical and it can not be used to describe the behavior of complex power system from the view of mathematical point.Even if not consider the mathematical rigor and forced the sensitivity method applied to the production practice of complex power system,the method also exist the following problems:the contradictions between decoupling arithmetic and coupling parameter of power system affect the accuracy of calculation.Aiming at the problems above sensitivity method,this paper proposes a new method to calculate the electric distance namely complex power increment method.Through differentiating the analytic relationship between on line injection and send power can get the complex increment and then calculate the electric distance.And verify the feasibility,reasonableness and accuracy of proposed method compared with the sensitivity method by the results of IEEE39 nodes system partition.