Research On Optimal Control Strategy Of Power Flow System

With the increasingly shortage of the global energy, the ecological environment has been greatly harmed. As more attention has been drown worldwide to the development and utilization of renewable energy that has become an important issue in modern society. Tidal current energy with strong regularity and stability has more obvious advantage than other new energy.Tidal current generation system includes cross technology fields, and the development history of it is relatively short. So there are many key technologies to be solved. In the tidal energy power generation system, the working impeller is pounded by the changing trend, and the transmission system is vulnerable to be impacted by large load. So the power will fluctuate, which will lead the equipment to be failure. Especially for an independent power system, the technology of improving the energy capture efficiency and guaranteeing the quality of electric energy is still not perfect. This paper studied the optimization control technology of tidal current generation system, by concluding a large number of domestic and foreign research on tidal energy power generation technology.In this paper, the semi-submersible catamaran is adopted as a power platform, which is similar to fairing principle, concentrating flow rate and improving the turbine efficiency. Anchoring manner is used to solve the problem of self-convection when flow direction changing. Power generation device is arranged inside the catamaran, which can make the unit safety work and is also convenient for operating personnel.To solve the problem of the power generation system’s inefficiency in low velocity, under the condition of unknown tidal current velocity, the hydraulic drive system is designed based on the principle of maximum energy capture. And an improved climbing method is applied by changing the step size disturbance to adjust the pump displacement, thus changing the anti-torque of pump to make the impeller stably real-time track the maximum power point at different flow rates. For the problem of power instability by the flow change, a series of energy conversion is made by the electrical system components. Voltage and frequency stability is achieved by regulating the DC converter switch off which adopted pulse width modulation technology regulated by fuzzy self-tuning PID control.On the basis of the system theoretical analysis, to verify the accuracy and effectiveness of the control system, the mathematical models of the tidal energy capture, hydraulic transmission, generator, electrical control and so on are established and the Matlab/Simulink combined the AMESim software was used to complete the modeling and simulation of system. Then 9kW hydraulic type horizontal axis tidal current energy generator is built as sea test device and sea trials is conducted. The results of simulation and experimental verify the reliability and validity of the proposed current generation control strategy in this paper.