Two different operating modes can be clearly identified in wind turbine control systems. In low wind speeds, the main control objective is the energy capture maximization, whereas in high wind speeds it is desired to regulate turbine power and speed at their rated values. The fulfillment of these different control objectives implies the transition through low controllability operating conditions that impose severe constraints on the achievable performance. The control task is usually tackled using two separate controllers, one for each operating mode, and a switching logic. Although satisfactory control solutions have been developed for low and high wind speeds, controller design needs refinement in order to improve performance in the transition zone. This chapter overviews a control scheme covering the entire operating range with focus on the transition zone. H_∞ and advanced anti-windup techniques are exploited to design a high performance control solution for both operating modes with optimum performance in the transition zone.

关键词：抗饱和；增益调度控制；H_∞最优控制

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Actually, variable speed wind turbines are continuously increasing their market share, since it is possible to track the changes in wind speed by adapting shaft speed, and thus maintaining optimal power generation. The more variable speed wind turbines are investigated, the more it becomes obvious that their behavior is significantly affected by the used control strategy. Typically, they use aerodynamic controls in combination with power electronics to regulate torque, speed, and power. The aerodynamic control systems, usually variable-pitch blades or trailing-edge devices, are expensive and complex, especially for larger turbines. This situation provides a motivation to consider alternative control approaches. This chapter deals, therefore, with high-order sliding mode control of doubly-fed induction generator-based wind turbines. This kind of control strategy presents attractive features such as chattering-free behavior (no extra mechanical stress), finite reaching time, and robustness with respect to external disturbances (grid faults) and unmodeled dynamics (generator and turbine). High-sliding mode control appropriateness will be highlighted in terms of sensorless control and enhanced fault-ride through capabilities. Simulations using the NREL FAST code will be shown for validation purposes.

关键词：风力发电机组；双馈感应发电机；高阶滑模

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The HHE Program evaluated employee concerns about exposures and health problems at a tire manufacturing plant. After evaluating the ventilation system, investigators determined that the general and local exhaust systems were operating properly. 

关键词：大气；室内气体；气体健康

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This chapter describes D-SIORHC, a distributed MPC algorithm with stability constraints based on a game approach. This controller is designed for chained linear systems, in which each local subsystem interacts only with their neighbors. At the beginning of each sampling interval, each local controller agent computes the value of the corresponding manipulated variable in an iterative process where, in each iteration, it optimizes a quadratic cost by assuming that the neighbor controllers will use for their manipulated variables the value which they have computed in the previous iteration. Therefore, in a game theory framework, if this coordination procedure converges, a Nash equilibrium is reached. The use of linear plant models and the absence of inequality operational constraints allows to compute the manipulated variables in an explicit way, in each iteration of the coordination procedure, thereby reducing the computational load. This approach differs from other distributed MPC algorithms based on linear models in the inclusion of stability constraints in the local controllers that leads to a different control law. The controller usage is illustrated through its application to a water delivery canal.

关键词：分布式MPC；游戏；控制器

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This chapter presents a control scheme of a variable-speed wind turbine with a permanent-magnet synchronous-generator (PMSG) and full-scale back-to-back voltage source converter. A comprehensive dynamical model of the PMSG wind turbine and its control scheme is presented. The control scheme comprises both the wind-turbine control itself and the power-converter control. In addition, since the PMSG wind turbine is able to support actively the grid due to its capability to control independently active and reactive power production to the imposed set-values with taking into account its operating state and limits, this chapter presents the supervisory reactive-power control scheme in order to regulate/contribute the voltage at a remote location. The ability of the control scheme is assessed and discussed by means of simulations, based on a candidate site of the offshore wind farm in Jeju, Korea.

关键词：永磁同步发电机；风力发电机组；风电场

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This chapter proposes a methodology to design robust control strategies for wind turbines. The designed controllers are robust, multivariable and multi-objective to guarantee the required levels of stability and performance considering the coupling of the wind turbine. The proposed robust controllers generate collective pitch angle, individual pitch angle and generator torque control signals to regulate the electrical power production in the above rated power production zone and to mitigate the loads in the components of the wind turbines, like the drive train, tower, hub or blades, to increase their lifetime. The synthesis of these controllers is based on the H_∞ norm reduction and gain scheduling control techniques via Linear Matrix Inequalities. A wind turbine non-linear model has been developed in the GH Bladed software package and it is based on a 5 MW wind turbine defined in the Upwind European project. The family of linear models extracted from the linearization process of the non-linear model is used to design the proposed robust controllers. The designed controllers have been validated in GH Bladed and an exhaustive analysis has been carried out to calculate fatigue load reduction on wind turbine components, as well as to analyze load mitigation in some extreme cases.

关键词：风力发电机组；鲁棒控制；多变量控制

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The number of degree of freedom (DOF) in an actuator system determine the number of modes it capable of, higher DOF means more modes. On a bilateral control system, if the master system has different DOF from the slave system then the difference of DOF between master and slave will cause a problem since it is impossible to lower DOF system to realize all of the modes of higher DOF system. Bilateral control using different structure system is very useful for controlling a complex system such as finger robot system. By using a master that has a lot of DOF will make the operator feel familiar and comfortable to operate the finger robot, while slave that has little DOF will make the slave robot lighter and smaller. But most of the existed research deal with bilateral control system using master system that has lower DOF than slave system. This study tries to realize bilateral control system using master system that has higher DOF than slave system by a mode based bilateral control system. The proposed method uses transformation matrix to obtain the mode of master and slave system, and then the mode information of both systems will be used to realize bilateral control. The experimental result shows that the proposed method is working.

关键词：双向控制系统；范式转换；模态控制

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The Health Hazard Evaluation (HHE) Program evaluated employees' exposure to lead when working in the parking garage adjacent to the firing range of a police department.

关键词：大气；空气污染；废气排放

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In April 2012, National Institute for Occupational Safety and Health (NIOSH) researchers and the Silica/Milling-Machines Partnership coordinated by the National Asphalt Pavement Association (NAPA) conducted laboratory testing of a local exhaust ventilation (LEV) system on a Roadtec RX600e cold milling machine. The testing was conducted indoors at the Roadtec manufacturing facility in Chattanooga, Tennessee. All tests were conducted on a stationary milling machine with the cutter drum and conveyor belts moving, but without any reclaimed asphalt pavement (RAP) moving through the system. Smoke and tracer gas were used as surrogates for silica dust to evaluate capture efficiencies of the dust emission-control system in the cutter drum housing of the machine. Smoke was used as an initial qualitative test to visually check for leaks. Sulfur Hexafluoride (SF(6)) was used to quantitatively evaluate capture efficiency of tracer gas released in the cutter drum housing of the machine. Two independent analytical instruments were used to measure the resulting SF(6) concentrations in the LEV exhaust duct, an Innova AirTech Instruments 1412 Photoacoustic field gas-monitor and a Miran SapphIRe infrared spectrometer. Capture efficiency tests were conducted at a single flow rate on the Roadtec cold milling machine. The mean capture efficiency from the Innova AirTech Instruments 1412 Photoacoustic field gas-monitor and Miran SapphIRe data were 98% and 99%, respectively. The lower 95% confidence limits were 97% for both the Innova AirTech Instruments 1412 Photoacoustic field gas-monitor and Miran SapphIRe results. Additional testing during actual milling activities is recommended to document capture efficiency under true field conditions. The testing reported here only evaluated capture efficiency within the cutter drum housing. Other potential dust release locations on the machine such as the transition between the primary and secondary conveyor and the top of the secondary conveyor were not evaluated during this testing but could contribute to silica exposures during actual field operation.

关键词：大气；气体流通；空气健康

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The mixed controller design problem of Dynamic Positioning Systems for Ships (DPSS) is discussed in this paper. Based on the H_2 control scheme, passivity theory and Lyapunov function, the sufficient conditions are derived into Linear Matrix Inequality (LMI) problems which can be solved by convex optimization algorithm. Therefore, the mixed performance controller can be designed via solving proposed sufficient conditions for guaranteeing the mixed performance of DPSS with minimized output energy and initial conditions. Finally, the simulation results are presented to demonstrated the effectiveness and useful of the proposed design method.

关键词：DPSS；混合性能；无源化； H_2方法

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