Much medium and low temperature waste heat is produced in the cement production process,and using waste heat power generation is an important means of energy saving of cement production enterprises. In order to keep the power stability of the waste heat power generation system, taking a single machine infinite bus power system as an example, a mathematical model of waste heat generator excitation system is established, and the excitation controller of synchronous generator is designed based on the exponential terminal sliding mode variable structure control theory. For the three-phase short circuit and three-phase circuit breaker fault of the power system, time domain simulation is performed by MATLAB, showing that exponential terminal sliding mode variable structure control system has better adaptability and stability compared with the fast terminal sliding mode variable structure control simulation result.