1.it is better to use sequence control in auxiliary process systems which frequently need regular operation.
2.The sequence control system of the power plant contains sequence control system for the main engine and auxiliary engine of the power units and the sequence control system for the power plant auxiliary systems.
3.The sequence control for the power units should take the sub-function as the principle thing, which implements the  sequence control for the related equipments of the auxiliary process systems.
4. When the power units sequence control function can not be contained in the distribute control system, its function should implement through programmable controller. There should be a communication connection between the programmable controller and the distribute control system. The switch quantity of auxiliary process systems could implement through the programmable controller. 
5.The design of sequence control should complies with the principle that protection and interlock operations are preferential. When protection and interlock orders appear during the process of sequence control, the control process should be broken off and make the process system follow the protection and interlock orders. 
6. If any failure happens to the sequence control or it is interrupted by operation people when it runs automatically, the ongoing program should be interrupted, and the process system should be in safe state.
7. Sequence control system should have measures to prevent wrong operation.