نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه مهندسی آب، دانشکده فناوری کشاورزی، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران،
2 گروه مهندسی آب، دانشکده فناوری کشاورزی، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران
3 گروه مهندسی آب، دانشکده فناوری کشاورزی (ابوریحان)، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In this study, the performance of a Proportional-Integral (PI) automatic control system for the operation of the main channel of the northern branch of the Abshar irrigation network was evaluated under low-water operation scenarios. The actions taken to achieve the research objectives included:1) Development of a hydraulic flow simulation model in the main channel of the Abshar irrigation network using a simplified Integral-Delay (ID) mathematical model. 2) Development of a decentralized PI automatic control operation model. 3) Coupling the automatic operation control model with the hydraulic simulation model in MATLAB and determining the proportional and integral coefficients of each controller using system identification methods. 4) Simulation of the operation status using the designed automatic system under normal, low-water, and severe low-water operation scenarios with input fluctuations. The simulation results demonstrated that the controller had acceptable capability in implementing desirable operation under normal operation scenarios, with performance evaluation indices MAE, IAE, and STE fluctuating within the ranges of 0.11 to 0.140, 0.0013 to 0.0182, and 0.0001 to 0.0011, respectively. With the emergence of low-water scenarios and their intensification, water distribution conditions were assessed as desirable in upstream intakes but uncertain in downstream intakes. The calculated maximum error values in the lower intervals ranged from -10 to -20 and -35 to -45 centimeters, respectively. The results showed that the controller transferred the effects of low-water conditions and inflow fluctuations downstream, resulting in desirable surface water distribution for upstream intakes but inappropriate distribution for downstream intakes.
کلیدواژه‌ها [English]
Developing a decentralized proportional-integral automatic control system and evaluating its performance in improving the operation of the Abshar irrigation district’ main canal
EXTENDED ABSTRACT
Given the emergence and intensification of drought periods and the increase in irrigated agricultural land, exacerbating the demand for agricultural products, pressure on surface and groundwater resources has become a similar problem. Upgrading the operation of irrigation channels has become particularly important in many countries. Automation of surface water distribution systems through upgrading water level regulation methods and daily water distribution and delivery planning by automatic control systems is one of the effective solutions to improve agricultural water productivity. In this regard, in this study, while developing a Proportional-Integral (PI) automatic control algorithm, as an automatic control system for the operation of the main channel of the northern branch of the Abshar irrigation network, its performance was evaluated under low-water operation scenarios.
The first step in developing an automatic control system for the main channel of Abshar was the development of a hydraulic flow simulation model to simulate hydraulic parameters such as water level and flow rate along the channel. In this study, a simplified Integral-Delay (ID) mathematical model for hydraulic flow simulation was developed and calibrated and validated using measured data. Subsequently, a decentralized Proportional-Integral (PI) automatic control operation model was designed for channel segments and coupled with the hydraulic simulation model using MATLAB. Then, the proportional and integral coefficients of each controller in this system were identified using the System Identification method. Finally, the operation status was simulated using the designed automatic system under normal, low-water, and severe low-water operation scenarios with input fluctuations, and the performance was evaluated.
Simulation results showed that the decentralized Proportional-Integral (PI) control system demonstrated acceptable capability in implementing desirable operation along the main irrigation channel under normal operation scenarios. The calculated maximum error values in intervals 6 to 10, 11 to 15, and 16 to 20 were variable within the ranges of -6 to -9, -11 to -13, and -13 to -18 centimeters, respectively. Based on these, performance evaluation indices MAE, IAE, and STE obtained values of 0.11 to 0.140, 0.0013 to 0.0182, and 0.0001 to 0.0011, respectively. With the emergence of low-water scenarios, water distribution conditions were assessed as desirable in upstream and midstream water intakes, while downstream intakes were deemed uncertain, with calculated maximum error values in the lower intervals of 16 to 20 ranging from -10 to -20 centimeters. In severe low-water scenarios accompanied by fluctuations, only upstream intakes experienced desirable water delivery conditions, while downstream intakes experienced poor operation. In these conditions, the calculated maximum error values in intervals 11 to 15 and 16 to 20 were variable within the ranges of -17 to -22 and -35 to -45 centimeters, respectively. Based on these, performance evaluation indices MAE, IAE, and STE obtained values of 0.096 to 0.172, 0.0123 to 0.0991, and 0.0089 to 0.0592, respectively.
The results indicated that the designed decentralized controller transfers the effects of non-standard phenomena at the input water intake to the network at the diversion structure location (in this study, low-water conditions and fluctuations) downstream. As a result, disturbed and inappropriate surface water distribution occurs at the downstream water intakes of the network.
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