Networked Control Systems And Its Application In Hydropower Plant

Along with the extension of the control system scale and fast development of network technologies, control systems based on networks are widely applied in the modern industry control, which have advantages of less wires, high reliability, good flexibility and share of information resources, etc. However, since the communication network has been inserted in the networked control system, some new issues such as network-induced time delay, network scheduling, multiple-packet transmission and dropping network packets appear. Therefore, analysis and design of NCS has been a hot research problem in the control theory and control engineering area.The chief researches of this paper are showed as follows:(1) Introduce several kinds of fieldbuses that are used widely at present. Emphasize on analysing the features of CAN and the structure of the CAN bus protocol .Finally the NCS constituted by CAN bus and its time delay are analysed.(2)The principle,basic structure and communication task of the supervisory control system (SCS)of hydropower plant are introduced in the thesis.The configuration of the full-distrubuted and full-open SCS based on CANBUS are expatiated.(3)To the existing network-induced time delay, differentmethods for time-delay compensation in NCS are introduced based on modeling of NCSAs for uncertain time delay, some combined compensation schemes including Fuzzy-PI controller and Fuzzy-PI controller based on Smith prediction are presented firstly ;then Stabilization is analyzed, These control methods are validated through the simulation of network-based controlled water pump frequency converted control system.(4)The performance of NCS is not only dependent on control algorithm,but also dependent on scheduling .Two typical scheduling algorithms are introduced in this thesis and analysed through the NCS simulation toolbox — TrueTime.NCS scheduling optimization is studied from the point of view of the network.