Research On Transmission Capacity Of Trans-region Or Trans-provincial Channel In Complex Power Grid

Under the advance of the new electricity market reform,the power transaction between power grids tends to be longer and larger,and the power exchange between sections is more frequent.Simple static stability constraints can no longer meet the requirements of actual power grid security and stability operation.Transient stability is a problem that can not be ignored in regional connection.Sensitivity analysis is an effective way to calculate TTC since the early stage.It can take into account the actual power grid structure and operation characteristics,consider the system’s regulation and control mode.At the same time,the static and transient stability constraints of the system are considered,the calculation principle is simple,it can directly reflect the relationship between nodes and transmission lines and loads,and has been widely applied.The interconnection of large power grids makes the system more complex.To solve this problem,the relationship between system nodes is simplified by the sensitivity analysis methed,which can intuitively reflect the relationship between the two nodes.On the basis of comprehensively considering the static stability and transient stability of the system,taking the transmission section of central China power grid as an example,is analyzed and calculated on the main transmission section of the maximum transmission capacity.Results show that,the thermal stability and transient stability constraints are the main transmission capacity constraints.The calculation results can be used as a reference index for the actual safe and stable operation of the power grid.Aiming at the shortcomings of sensitivity analysis method,the power flow tracing method is further proposed,considering the nonlinearity of the system.It can accurately reflect power distribution of power grid generator output to transmission line and load node,and use the calculated power distribution coefficient to eliminate transmission lines which are not closely connected with the power grid,simplify the calculation process and reduce the calculation time.In the end,the maximum transmission capacity of the system is calculated by the power flow tracing method with the example of the district power grid,and the results are compared with the sensitivity analysis method to illustrate the feasibility and the reasons for the difference between the results of the two calculation.