Dynamic Simulation and Effect Analysis of Power Load Unbalance Protection for the Turbo-Generator Unit

The turbine with power load unbalance protection (PLU) can restrain the rotor speed rise and avoid speeding when a turbo-generator unit meets load rejection. However, due to the poor reliability of power measurement, it is easy for the PLU protection to malfunction and bring serious impact to the safety and stability of the unit when operators take improper operation or measurement problems take place. A dynamic simulation model is established, which can simulate the dynamic performance of the overs-peed protection control (OPC) and the PLU protection, the influence of the action on the unit speed, power, main steam pressure and other parameters when the load rejection occurs. In addition, the life of the unit can also be evaluated by this model. Then an example of a 1050 MW ultra supercritical steam turbine is calculated and analyzed, in which the performance of over-speed protection system, changes of thermal parameters including rotor speed, unit power, main steam pressure, and so on in two cases of power load unbalance protection and no power load unbalance protection when the load rejection takes place. This paper gives discussion and analysis about the rationality of PLU protection in a turbo-generator unit.