Abstract
In steam turbine control and actuation, the steam control valve plays a key role in operability and reliability. The electrohydraulic regulating system for the steam control valve, usually called the servomotor, needs to be reliable and high performing under nonlinear excitation interference in actual conditions. Currently, electrohydraulic servo valve control technology is widely used in servomotors. Although this technology has good control performance, it still has some technical defects, such as poor antipollution ability, low energy efficiency, large volume size, and limited installation space. Aiming at the abovementioned technical shortcomings of electrohydraulic servo valve control technology, a servomotor-pump-hydraulic cylinder volume control scheme is proposed in this paper, forming a pump-controlled servomotor for the steam control valve. By analyzing the working principle of the pump-controlled servomotor position control in the steam control valve, the mathematical model of a pump-controlled servomotor for the steam control valve is established. The sliding mode variable structure control strategy is proposed, and the variable structure control law is solved by constructing a switching function. To verify the performance of the proposed control method, experimental research was conducted. The research results show that the proposed sliding mode variable structure control strategy has a good control effect, which lays the theoretical and technical foundation for the engineering application and promotion of pump-controlled servomotors for steam control valves and helps the technical upgrade and product optimization of steam turbines.
Highlights
The steam turbine uses high-pressure steam produced by the boiler to rotate its main shaft, and the main shaft drives the generator through a hydraulic coupling to generate electricity by excitation
As the most widely used prime mover equipment in the power industry [1], the steam turbine is widely used in the metallurgical industry, chemical industry, and ship power systems [2,3]
This paper studies the position control of the PCSM for steam turbines, analyzes the working principle of the PCSM, and establishes the mathematical model of the PCSM
Summary
The steam turbine uses high-pressure steam produced by the boiler to rotate its main shaft, and the main shaft drives the generator through a hydraulic coupling to generate electricity by excitation. In the load and full load stages, the SM changes the intake of high-pressure steam by adjusting the steam control valve, thereby regulating the power of the system This allows the steam turbine to meet the changing needs of users’ electricity consumption while ensuring that the speed is within the normal range. The high-performance control of the servomotor plays an important role in the quality adjustment of power and frequency for steam turbines and is significant. This paper studies the position control of the PCSM for steam turbines, analyzes the working principle of the PCSM, and establishes the mathematical model of the PCSM On this basis, a sliding mode variable structure control strategy is proposed [20,21,22,23,24,25,26]. The system robustness is improved, and the high-precision control of the SM position is realized
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