Digital electrohydraulic control system of steam turbine with isolated network operation

Abstract

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 the steam turbine to keep the balance between the output of a steam turbine generator unit and the receiving load of the steam turbine generator unit; in addition, the speed measuring protection part takes an accelerated speed signal as a trigger condition of overspeed limit, thereby effectively limiting the rotating speed overshoot generated by the steam turbine generator unit because of load shedding.

Description

technical field [0001] The invention relates to a digital electro-hydraulic control system of a steam turbine, in particular to a method and a device for stabilizing the system frequency of a steam turbine generating set when a single machine or a small network operates. Background technique [0002] With the diversified development of the power system, the large power grid cannot cover all power supply needs. Under the following conditions, single-machine or small-network operation will still occur. [0003] my country's power grid has gradually developed from small to large. Under certain circumstances, large grids may be separated, and small grids may appear. In areas where large grids cannot reach, small grids still need to be used for power supply. Due to various reasons, the self-provided power stations of some factories need to be operated in an isolated grid. Units exported to underdeveloped countries may have to adapt to the requirements of isolated grid operatio...

AI Technical Summary

Problems solved by technology

In the practice of DEH, it is found that the stability of the DEH speed regulation system is much lower than that of the mechanical hydraulic speed regulation system. This is due to the sampling distortion and operation delay of the discrete control system, resulting in a decrease in system stability.

In most traditional DEH control systems, it is difficult to maintain the frequency stability of the isolated small grid, and it is also difficult to maintain the frequency stability of the isolated small grid that is split if the connection line of the large power grid fails.

Images