The steady-state stability and the features of stability limit on a wind-thermal bundled sending system are studied. A variable speed wind turbine with power electronic interface can control the power quickly and flexibly. In the steady-state stability analysis

by neglecting the fast dynamics of wind power regulation

the wind power is simplified to a static power injection model

and can be described as an algebraic equation in the system dynamic process. By proposing a triangular transformation model of the wind-thermal bundled transmission system

the change of steady-state stability limits on thermal generator and the sending interface with wind power is investigated. In the wind-thermal bundled transmission system

when wind power increases from zero

the steady-state stability limit on thermal generator decreases

and the limit on the sending interface first increases

then decreases. Simulation results in the test system and an actual system have validated the conclusion. This work is supported by State Grid Corporation of China(No. 52210015000S).