Industrial Control Engineering

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Browsing Industrial Control Engineering by Subject "ANN"

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    Design and Simulation of Speed Sensorless, FOC of Induction Motor Drive Using ANFIS Controller and ANN Estimator
    (Addis Ababa University, 2020-06) Biniam, Abera; Mengsha, Mamo (PhD)
    This thesis presents design and simulation of Artificial Neural Network solution for speed estimation including an ANFIS for control of IM drives. In the past years the research efforts in the field of IM control concentrated on the identification and observation of this highly nonlinear dynamic plant. Existing vector control methods require speed sensor for control and field orientation purpose, but their installation makes the drive system bulky, unreliable and expensive and installing them might not be feasible in some applications, such as motor drives in hostile environment or high-speed drives. In such cases speed is obtained from easily measurable stator quantities. Many speed sensorless techniques have been proposed to cope up with speed sensing problem. Developed speed estimation algorithms are more or less parameter dependent and/ or computationally time consuming. In this thesis, the proposed estimation method is based on ANN to obtain the speed signal. The conventional PI controller is replaced by an ANFIS which tunes the fuzzy inference system with hybrid learning algorithm. The ANN is used as estimator, trained by Levenberg- Marquardit algorithm. The data for training are obtained from conventional FOC simulations when the motor drive is working in closed loop at various values of speeds and loads for speed observation. The complete drive system is modeled using MATLAB®2019a. Finally, the drive results have been analyzed for both steady state and dynamic conditions such as of speed tracking capability, torque response quickness, low speed behavior, step response of drive with speed reversal and sensitivity to motor parameter uncertainty. The error of simulation result between actual and estimated speed have been less than 0.3% for transient response, 0.2% for speed tracking and 0.44% during low speed operation. It was observed from simulation results that by using PI and ANFIS controller, for the reference speed of 151rad/sec, the rise and settling time are improved by 0.0938 and 0.1289 seconds at full respectively also robust response is achieved with the latter controller.
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    Non-Linear Adaptive Control of Hydropower Generator Cooling System
    (Addis Ababa University, 2018-11) Yabebal, Adeyabeba; Dereje, Shiferaw (PhD)
    This thesis describes the use of nonlinear adaptive control to design the cooling system of hydropower generators. The increasing load demands are posing serious threats to reliable operation of power systems. These days, in the light of the attention given to reduction of carbon dioxide emissions and efficient usage of raw materials, high-efficiency electric generators are in the lime light over the world. As all losses generate heat it is important to have a cooling system that can maintain a sufficiently low operating temperature within all parts of the generator. The objective of this research was to model, design and simulate a reliable and efficient cooling system for hydropower generators using nonlinear adaptive control. As the load on a generator varies with time, the generators heat dissipation also varies. This variation in the heat causes the temperature of the air surrounding the generator in the closed generator room to vary. In this thesis this variation of temperature is studied and heat transfer analysis method is used to determine the heat loss of the generators. Following that appropriate size of butterfly valve is chosen which is driven by a DC servomotor and a tubular heat exchanger is designed using dimensionless number analysis method which includes determining the Reynolds number, Prandtl number, and Nusselt number. Then the required amount of cooling water is supplied through the tubular heat exchanger according to the load on the generator. In this research the cooling system is designed to keep the generator temperature below 50 C in other words keeping the temperature of the surrounding air inside the generator room below 27 0 0 C. Matlab Simulink software is applied for performance analysis of the designed cooling system. The simulation results show that the designed cooling system keeps the surrounding air at a temperature of 27 C with a settling time of 0.6 seconds and without any overshoot when it exceeds this set point (27 0 C). For this study we choose the Koka Hydropower Plant and the required data for the design is collected from there. The butterfly valve opening angle for adjusting the valve at the desired position in order to allow the required flow rate is related with the temperature of the generator room in a non-linear way specifically having an exponential relation. Thus an ANN controller is used which accounts for this process nonlinearity so that increasing model robustness and reducing the generator stoppage time due to cooling system failure. This results in increasing the efficiency of the hydropower plant as a whole.