Abstract:In order to study the dynamical model and characteristics of the process in which the motor speed of the centrifugal pump water supply system suddenly changes at different operating points, the experiment of model identification under speed regulation operating condition is conducted based on the design of centrifugal pump water supply experimental system with speed regulating which optimizes the outlet valve structure in water supply system. The new experiment system implement step disturbance as input signal and present the changes of operating points logically. Virtual instrument and high frequency electrical parameter measuring instrument are used for data collection. The experiment is designed based on the step response method, and the model structure is obtained from prior knowledge about this system, the model parameters are estimated in Matlab system identification tool box using the method of least squares. Based on the pole-zero diagrams obtained by Matlab, the changes on dynamical model parameters and characteristics of the system running at the speed-up condition and the speed-down condition are analyzed and compared. It is concluded that model parameters of this system change while the system runs at different operating points, the estimated model is minimum phase and stable, mathematical model for the system is second order inertia and lag structure. Real-time variable parameters identification and real-time control is more suitable for the system.
[1]Brookshire D S, Whittington D. Water resources issues in the developing countries[J].Water Resource Research, 1993, 29(7):1883-1888.[2]Mousavi H, Ramamurthy A S. Optimal design of multi-reservoir systems for water supply[J]. Advance in Water Resource, 2000, 23:613-624.[3]Lee Y W, Bogardi I, Kim J H. Decision of water supply line under uncertainty[J]. Water Resource Research, 2000, 34(13):3371-3379.[4]Gieling T H, Janssen H J J, Straten G V, et al. Identification and simulated control of greenhouse closed water supply systems[J].Computer Electronics in Agriculture, 2000, 26:361-374.[5]Cembrano G G, Wells J, Perez Quevedo R, et al. Optimal control of a water distribution network in a supervisory control system[J]. Control Engineering Practice 2000(8):1177-1188.[6]王柏林,李训铭. 变频调速泵供水系统分析[J]. 河海大学学报:自然科学版,1995,23(2):104-106. Wang Boling, Li Xunming. Analysis of water supply system of variable-frequency pump[J]. Journal of Hohai University:Natural Science Edition, 1995, 23(2):104-106.(in Chinese)[7]Obradovic D. Modelling of demand and losses in real-life water distribution systems[J]. Urban Water, 2000(2):131-139.[8]Elbelkacemi M, Lachhab S, Limouri M, et al. Adaptive control of a water supply system[J].Control Engineering Practice, 2001(9):343-349.[9]Chang Weider. Nonlinear system identification and control using a real-coded genetic algorithm[J]. Applied Mathematical Modelling, 2007,31(3):541-550.[10]Eker I, Kara T. Modeling and simulation of water supply systems for feedback control[C]//36th Universities Power Engineering Conference: Power Utilisation, Part-5C. Swansea:[s.n], 2001.[11]曾云,张立翔,钱晶,等. 弹性水击水轮机微分代数模型的仿真[J]. 排灌机械工程学报, 2014, 32(8): 691-697. Zeng Yun,Zhang Lixiang,Qian Jing,et al. Differential algebra model simulation for hydro turbine with elastic water column[J]. Journal of Drainage and Irrigation Machinery Engineering, 2014, 32(8): 691-697.(in Chinese)[12]王乐勤,王循明. 离心泵变频调速变压供水系统设计模型及求解[J]. 流体机械,2003,31(9):15-17. Wang Leqin,Wang Xunming. Design of variable-pressure and frequency-conversion for centrifugal pump water supply system and the calculation for optimized model[J]. Fluid Machinery, 2003, 31(9): 15-17.(in Chinese)[13]丁周伟. 泵站恒压供水系统的设计与实现[D]. 哈尔滨:哈尔滨工业大学能源科学与工程学院,2006:6-8.[14]孔繁余,何玉洋,邵飞,等.转柱泵瞬时流量的理论推导及数值模拟[J]. 江苏大学学报:自然科学版,2014,35(1):29-33. Kong Fanyu, He Yuyang, Shao Fei, et al. Theoretical derivation and numerical simulation of instantaneous flow rate for pillar pump[J]. Journal of Jiangsu University:Natural Science Edition, 2014, 35(1):29-33.(in Chinese)