Yangquan No.2 Power Plant DEH System Analysis

Connecting with the principle of autocontrol, this text introduces the DEH system from the angle of turbine project. It analyzes the constituting, control function and the logic of the DEH system . Connecting with traditional analysis principle for turbine control characteristic and DEH system working practice, this text further analyzes the originative control characteristic of DEH system .This text is for the purpose of perfecting better the concept of DEH system, and making both of turbine project and autocontrol project could understand the DEH system more completely, and functioning for instructing power plant practice maintenance . This text introduces the characteristic concept of turbine control system from two traditional aspects of static and dynamic state, and the characteristics of reheating system and the power- frequency electric liquid control system, and analyzes the difference from the simulated electric control system to digital electric system.This text describes the constitute of DEH system from three aspects and analyzes the reliability of DEH system . We can understand the thoughts of the DEH design and the relation of every parts to DEH reliability by learning the main logic and liquid system of DEH.This text finally analyzes the control characteristic of DEH system. By the analysis of DEH system and running practice ,DEH control logic are complicated but careful, control function strong .The characteristic of DEH system have improved very much to traditional system .The DEH system can easily changes the static curve, and makes the transfer from difference to non-difference control.That the PID controller coefficient of DEH system can easily adjust according to the experiment make dynamic characteristic better, and can make a brief overopen for good first frequency modulation ability . Because DEH system can use feedback signal of the first class pressure as practical power of turbine, it can avoid the reverse control, have the good ability of anti-disturbing.By the sophisticate control logic DEH can make swift change of the control demand for following best value according to the circumstance , largely improved the dynamic characteristic when the unit sundenly discharge the full load . DEH oil system adopts high pressure dynamic phosphoric acid grease anti-ignite oil, performance is stable, the time constant of oil-driving machine and the inertia power are less. The oil system have accumulator to absorb hydraulic surge.Adopting the inside high accurate electromagnetism servo valve with the negative motive feedback spring coil can avoid the control process surve , dynamic characteristic is excellent. In despite of superior function of the DEH system is very outstanding, but this text finally also analyzed some places of its shortage.