The Research Of Fault-Tolerant Control For Wind Energy Conversion System

Energy is the essential element for human, and also is the material basis for economic development. Earth's fossil fuels will eventually tend to depletion through millions of years of immense waste. It is extraordinary significance for easing the energy shortage by using the renewable resources such as wind, as the most important one of clean alternative energy. With the rapid development of wind power generation, wind power technology research has become the world's hot spots for how to get the most control of wind power and system reliability of a series of key issues such as scholars have been more and more attention. As the wind power with a rapid development, its technology has also developed with the expended market, especially on the maximize the efficiency of captured wind energy and reliability control have windly concerned. As the wind energy conversion system is composed by mechanical transmission parts, generator parts, and some networks, considered the complexity of the system, when the sensors, actuators and other components become fault, the system can work as usual, and that give a new requirement for the tolerant control. In this context, this paper discusses the fault tolerant control methods in the wind energy conversion system, and the details show as follows:According to the multi-time scale mathod of the wind speed, with the wind speed dividing into low-frequency part and high-frequency part by the frequency separation theory. The low-frequency-loop is established by steady-state control and the high-frequency-loop is established by turbulent control.The paper designs a H∞fault-tolerant controller based on the two-frequency-loop model, so that realize the fault-tolerant control of the WECS which have certain parameters. When part of the sensors failure fault of the system, the low-frequency-loop use PI control, as the output could be stabilized to provide a stable system state model for the high-frequency-loop, and the high-frequency-loop adopt the robust fault-tolerant to control the loop, making system in case of sensor failure to stability.When part of the actuators failure fault under an uncertain systems, the low-frequency-loop use PI steady-state optimization control, and the high-frequency-loop adopt the robust fault-tolerant control, which make the system running stable under the faults. The simulation results show that the design of the robust fault-tolerant control method in the wind energy conversion system to be effective in this paper.For the two-frequency-loop model of the WECS with fault observer, the paper designs optimal fault-tolerant controller. When the drive train is rigid, part of the sensors and actuators failure fault, using a reduced order fault observer to detect the state of fault and the state of the system at the same time, then adopt a optimal fault-tolerant control, and then maximize the efficiency of captured wind energy, as well as the system work well when the sensors and the actuators are error. For the flexible drive train, when the sensors are error, by using a sliding model fault observer to detect the sensors fault and the state of the system at the same time, then adopt an optimal fault-tolerant control to ensure the system can operation normally when the sensors are error, and then maximize the efficiency of captured wind energy. The simulation results show that the design of the optimal fault-tolerant control method in the wind energy conversion system to be effective in this paper.