Patent ID: 8907508

Claim:
A load protection system for a turbine, the turbine having a load floor representing a lowest allowable load the turbine generally operates above, the turbine coupled to an electrical generator for a generation of electrical power to supply to an electrical grid, the electrical grid having a grid frequency where as the grid frequency increases the turbine sheds load, the load protection system comprising: the generator having a rotational speed, and wherein the grid frequency is dependent on the rotational speed of the generator; a controller in communication with the turbine and the electrical grid, the controller having a memory for storing a commanded target turbine load, the commanded target turbine load being the load the turbine operates at the load floor, the controller being configured to: define a nominal grid frequency for the electrical grid using a control variable; monitor the turbine for a commanded turbine load, the commanded turbine load being a load of the turbine prior to a change in the grid frequency; calculate a grid frequency limit, the grid frequency limit representing the grid frequency as the turbine operates at the load floor, the grid frequency limit based on the nominal grid frequency, the commanded turbine load, and the commanded target turbine load; compare the grid frequency limit with a filtered grid frequency and determine if the filtered grid frequency is at least about equal to the grid frequency limit; set a flag in the event that the filtered grid frequency is equal to or exceeds the grid frequency limit; and send the flag to a variable rate limiter and a commanded load control block, the variable rate limiter and the commanded load control block generally preventing the turbine from shedding load and operating below the load floor once the flag is received.