Research On Comprehensive Dynamic Equivalence Of500kV Power Grid And Its Application In DSR

With the rapid rise of the global industrial economy, the totalelectricity rises rapidly. In order to meet user’s requirements, the topologyof the power grid is becoming more and more complex. The complexity ofthe power grid increases the potential safety hazard in the process of powersystem operation. So, dynamic security assessment is particularly importantfor power system. For complex power network, as a method that canrepresent system dynamic security features, Dynamic Security Region (DSR)faces the following two questions: heavy computational burden and longcomputing time. So, in order to obtain DSR fast and accurately, applyingdynamic equivalence in the computation of DSR, that can make the systemdimension reduction and greatly reduce computational burden of the DSR.On the basis of correlation coefficient, this paper puts forward a newdynamic equivalence method that based on improved correlation coefficient.Cohomology relationship between two generators is judged by the analysisof state matrix. Compared with other methods of dynamic equivalence, thisarticle gives a detailed formula of correlation coefficient, and it is notlimited to size of power system and nonlinear effects. Through thesimulation analysis of IEEE10machine39node system, the simulationresults verified the feasibility of the method and its application in DSR.In500kV power grid, low voltage part’s topological structure has littleeffect on the dynamic characteristics of500kV lines and whole system.According to that, this paper puts forward a rapid dynamic equivalencemethod for DSR based on low voltage part of500kV power grid. Comparedwith traditional dynamic equivalence, its equivalent process is simple anddoesn’t consider the topology, the calculation burden is small. Thesimulation of test system verified this method is feasible to low voltage partof500kV power grid.For500kV power grid, in order to achieve the best dimension reductionand shorten the calculation time of DSR, this paper combines the above twokinds of methods and apply the comprehensive dynamic equivalence in theDSR calculation process of500kV power grid. Based on the simulation of500kV testing system, in the DSR calculation of500kV power grid by comprehensive dynamic equivalence, DSR calculation time was only about10.69%of the original system, the error of probability unsafetymeasurement is only2.96%, that verified comprehensive dynamicequivalence is feasible in the DSR computation of500kV power system.