Voltage Stability Analysis Considering Power Network Topology Optimization

The scale of power system becomes larger and the modern society is more dependent on the power supply excessively, so the safety and high quality operation of electric power system are more significant, and the voltage stability of power system is one of the most important issues.On the other hand, increasingly complicated power system network topology is not to be neglected to assure the safety operation, little by little.Although, the study of the voltage stability has a lot of breakthrough,in recent years,the combinations of the topological optimization seems not to be taken seriously. This paper which presents the ideas of the voltage stability considering the topological optimization is based on the background,trying to find a new view and a new way, and the main research contents are summarized as follows:Firstly, combining complex grid theory, the paper points out the power network has both the small world and scale-free property, and four structure parameters of the standard system are analyzed, and use the adjacency matrix with Kamada-Kawai arithmetic to simulate the real power grid in the Pajek.The key links are found based on the contraction node method and power load coefficient, on this basis, and verified in IEEE-39 and IEEE-118 nodes system.Secondly, the mechanism of voltage stability is introduced in the paper, and the steady state stability indices are proposed.For calculating the index of static load margin and the static voltage stability limit of power,and to overcome the singularity of Jacobian matrix when the load flow calculation reaching the limts,the continuation power flow which composed of four steps is presented.On the IEEE-39-bus test system it is verified, which involves the selection of time steps, different load growth rate, the active power and reactive power to the voltage support, and the placement of the network topology.Finally, non-coherence phenomenon in power transmission system is presented, and the topological optimization is brought into the control variable of the voltage stability meanwhile the mathematic model of optimization being proposed.The key link based on the complex network theory researched before is synthesized to optimizize the network topology on IEEE-39 and IEEE-118 test system,then voltage stability indices is compared with previous one,and it turns out to be correct which has more optimal topological structure.The advantages and disadvantages of the traditional control methods and topological one are compared by simulating three kinds of fault accident, and bringing the topological structure into the decision variable appropriately.The topology control is proved to be more advantages in mid-long term voltage stability,and the large scale power grid planning and its security operation are benefited from it.