Optimization Of Synchronization Performance In Power Grids Based On Power And Topology

Recent decades have witnessed a vigorous development of the power grids,the future power grids will sustain larger and larger fluctuations with the introduction of more and more renewable energies such as wind and solar power,the synchronization performance deteriorates correspondingly.So it is necessary to improve the synchronizability of a power grid,the research results have important reference value for the expansion of smart grid in the future.Considering the nodes power and the topological structure of power network,this paper uses the second-order Kuramoto-like model to model the dynamics of a power grid,and further analyzes the optimization of synchronization performance in power grids.The main contributions of this dissertation are as follows.1、A heterogeneous distribution method of the network coupling strength for improving network synchronization performance is put forward.At first,we use the Kuramoto-like model as the node model of the power grids,and use the local order parameters to describe the local synchronizability.After theoretical analysis and experimental simulation in IEEE39 and IEEE57 standard test grids,study shows that the nodes with high power are difficult to locally synchronize to their direct neighbors compared to low power nodes.Based on this finding,we propose a heterogeneous distribution method of the network coupling strength.Keep the total coupling strength the same,we increase the coupling strength of those links between high power nodes and their direct neighbor nodes,as well as links between the other related nodes,and reduce the coupling strength of those links between the rest nodes.Study shows that this method can reduce the critical synchronous coupling strength and improve the synchronization performance in a certain range.But when the heterogeneity of the coupling strength is too large,the synchronization performance of the network begins to deteriorate.2、This paper studies improving synchronizability of a power grid from two aspects,one is the power allocation of generators,the other is the adjustment of power grid topology with only adding one transmission line.This paper proposes a heterogeneous power allocation method where the power of a generator is inversely propotional to a max norm that is decided by the grid topology.The synchronizability of a power grid can be improved greatly with this heterogeneous power allocation method.Subsequently,when the power allocation is given,study shows that the synchronizability of a grid can be improved with adding one transmission line whose one endpoint is the generator node determined by the max norm,the other endpoint is the neighbors’ neighbor of the chosen generator node with the smallest degree.Simulation is carried on IEEE 14,IEEE 57 standard test grids and a BA scale-free network.Both theoretical analysis and numerical simulation verify the validity of the proposed method.Since synchronization performance and anti-interference performance of networks are positively correlated,the proposed method also can improve the disturbance resistance of a power grid.3、We study the synchronizability of power grids with power transmission in different connection types in interconnected power network.When building the model,in order to better reflect the interconnection characteristics of power grids.The connections between subnets should be as sparse as possible,therefore,we set the number of connection between power grids L=1,there are two types of connections between subnets.The connections with the node of the largest degree and connections with the random node.Simulation is carried on IEEE 14-39,IEEE 30-57 interconnected power grids,study shows that when the critical synchronous coupling strength of a large subnet is greater than the synchronous critical coupling strength of a small subnet,it can enhance the synchronization performance that a small subnet transmits the right power to a large subnet;when the critical synchronous coupling strength of a small subnet is greater than the synchronous critical coupling strength of a large subnet,it can enhance the synchronization performance that a large subnet transmits the right power to a small subnet.Since,according to the critical synchronous coupling strength of each subnet,it can be inferred that how the subnet transmits the right amount of electric energy is beneficial to improve the synchronization performance of the network.