Power and Load Unbalance protection modeling and parameter optimization

Abstract

Power and Load Unbalance protection (PLU protection) is one of major turbine protections to preventing steam turbine overspeed. The start condition is that if unbalance of mechanical power and electrical power exceeds the limitation, the PLU protection will be actuated to close the valves but not stop the generators. But the accidents have happened and power grid simulation show that the grid faults may make the PLU protection false trip, that maybe turn the valves on and off frequently, seriously, it may even create power oscillation. In order to solve this problem, the generator rotating speed constraint is introduced into the PLU protection and the simulation model is established in this paper. The setting method of rotating speed constraint parameter is proposed. The simulation results verify that this method can effectively prevent the PLU false trip and improve the reliability of PLU protection.