Digital electrohydraulic control system of steam turbine with isolated network operation

The invention discloses a digital electrohydraulic control system of a steam turbine with isolated network operation, comprising a control hardware part and a software logical operation part, wherein the control hardware part includes a speed measuring protection part, a one-time frequency modulation module, a servo control module, a man-machine interface part, a control unit and an input/output module; and the software logical operation part includes a first frequency modulation operation and secondary frequency modulation operation unit based on frequency deviation, an overspeed limit unit based on an actual rotating speed measuring signal and a logical judgment unit based on an actual power measuring signal. The control system carries out logical processing and operation on the frequency deviation and outputs a control signal to control an electrohydraulic servo valve through the servo control module to drive a servomotor so as to drive a valve to move, thereby controlling the steam admission quantity of t