The Study On Turbine Control In A Separated Power Grid

China has entered into the stage of the large power grid while the power construction developed, the virtue of the large power grid is significant, but the running of the separated grid is still needed, for instance, in2008the China south power grid experienced the snowstorm and lost a lot, the separated grid in some districts were requested to run normally to eliminate the loss. Some factory’s owned power plants need to run separately for some reasons, and the power units exported to developing countries have the same needs. So the turbine control system must have this function to meet the demands from the customers.When the generator gets rid of the large grid and switch into the separated grid, two control functions must be focused on by the DEH:one is to restrain speedup and avoid to trip, the other is to maintain the grid frequency effectively. While the turbine capacity becomes large and large, over speed problem will be serious, and load on the grid changes rapidly, etc. So the over speed protection becomes more important than before as well as getting the steadily situation after the unit switches into the separated grid from large grid.This paper describes the static feature and the delay rate feature of DEH system, analyzes that the primary frequency control makes the influence on the power plant and the users, and establish the mathematical model for the tubine-generater unit, and find the vital reason why it is hard to control the turbine speed when the unit get rid of the grid and go into the separated grid according to the stable judge formula of the turbine, then establish the control solution for the separated grid running, adopt the overspeed forecast technique to act in advance, raise the action setpoint of the overspeed control, and add in the secondary frequency control loop to keep the frequency stable.After constructing the simulation model for the turbine at factory and the test enviroment with the DEH system, and simulating the five different working condition while the turbine gets rrid of the large grid and goes into the separated grid running, the results show that the solutions on this paper reach the expected target and is valid to the turbine control in a separated grid.