COMPARATIVE ANALYSIS OF DYNAMIC PROPERTIES OF STEAM TURBINE SLIDE VALVE CONNECTION SCHEMES

The article discusses the advantages and disadvantages of different connection schemes of slide valves into the hydraulic section of electro-hydraulicregulation and protection systems of steam turbines. A comparative analysis of three schemes is presented, which are currently the most widely used insteam turbines of thermal power plants in Ukraine. In the first scheme, the slide valve is completely unloaded from the influence of pressures. Tointeract with the protection system, a spring-based disengagement mechanism is installed on the slide valve, separating the rods of the electromechanicalconverter and the slide valve stem. A ball switch is also installed, which controls the pressure in the hydraulic line supplying pressure fordisengaging the slide valve and electro-mechanical converter rods according to turbine protection system commands. In the second scheme, the slidevalve also has a spring-based disengagement mechanism between the slide valve rods and the electro-mechanical converter, but a turbine protectionline is connected directly to the slide valve. Actuation of the slide valve upon pressure release in the protection line occurs under the action of thedisengagement spring. In the third scheme, the disengagement mechanism between the slide valve and valve rods is implemented without springs,relying solely on the action of power pressure and protection-line pressure acting on the slide valve chambers. Actuation of the slide valve uponpressure release in the protection line occurs due to the power pressure. For each scheme, mathematical models were developed, consisting of systemsof nonlinear differential and algebraic equations. A computational analysis of the dynamic characteristics of slide valves within the three schemes wasperformed using the example designs of valves from K-160-130 and K-300-240 turbines. To evaluate dynamic performance, the turbine operatingmode during a sudden disconnection of the generator from the electrical grid was selected. The results show that the first scheme provides the bestresponse speed. The second and third schemes not only have lower response speed but also negatively affect the stability of pressure in the turbineprotection line. The use of the second scheme in systems where multiple slide valves must operate simultaneously under certain operating conditionsmay lead to an unintended turbine shutdown. In conclusion, the use of the first slide valve connection scheme is recommended. The obtained resultscan be used for the modernization of automatic control and protection systems of steam turbines when implementing electro-hydraulic control systems.