In order to solve the problem of strap-down inertial navigation system (SINS)/Doppler velocity log (DVL)/ultrashort baseline (USBL) system interference in complex underwater environment, an asynchronous sequential robust filter method is proposed in this article. The USBL original information of azimuth, slant range and altitude are introduced as the measurement information. The problem of large amount of computation caused by the high measurement dimension of multisensor information fusion is solved by introducing asynchronous sequential filter technology. Meanwhile, a robust Kalman filter (KF) algorithm is proposed, which is based on the Mahalanobis distance. The outlier detection is designed based on statistical characteristics. Finally, the effectiveness of the method proposed in this article is verified by simulation and River experiments. The experimental results show that the method proposed in this article can effectively eliminate outliers and improve the navigation accuracy while reducing the amount of computation.
In order to stabilize the fluctuation of wind power and maintain a stable power output, a complementary control idea is proposed. This idea aims to make the output power from two wind farms complement each other. This study proposes a distributed control strategy to solve the complementary control problem of wind turbines in two offshore wind farms on the basis of the Hamiltonian energy theory. The proposed control strategy not only ensures synchronization for wind turbines in the same farm but also keeps the combined output power of the two wind farms stable. First, through the Hamiltonian realization, the single-machine model of a wind turbine is transformed into a port-controlled Hamiltonian system with dissipation (PCHD). Subsequently, the Hamiltonian energy control law is developed on the basis of the energy-shaping method to adjust the Hamiltonian energy function. The complementary control of the two wind farms is designed to synchronize the wind turbines within an individual wind farm and keep the combined output of the two wind farms stable. Furthermore, the complementary control strategy is modified to address the communication delay between the two wind farms by incorporating time delay into the control problem. Finally, the effectiveness of the distributed complementary control has been verified via simulations.
It is found that the parameters of the negative capacitance circuit parameters have a great influence on the vibration amplitude of the piezoelectric damping vibration system with a negative capacitance circuit in experiment.The relation between the amplitude vibration of the piezoelectric damping vibration system with a negative capacitance circuit and the parameters of the negative capacitance circuit is derived.The simulations and experimentations are carried out.The theoretical simulation and experimental results show that the negative capacitance is closer to the capacitance of the piezoelectric patch,the effect of control is better.The series resistance is smaller,the effect of control is better.
This article first introduces the overall architecture and hardware configuration of the testing system based on PXI bus and LabWindows/CVI platform.Then it elaborates on the design scheme,the function and modules of the software,and the human-computer interface.Finally It is shown that the system can test and analyze the quality of data transmission through Fast/Gigabit Ethernet and CAN bus,and unpack the related protocol stack for analysis with the advantages of satisfactory realiability,stability,safety and praticability.
DC-input side of the inverter to balance input and output power, eliminate voltage fluctuation, and reduce the voltage spike in the input side. The reliability study on DC-link capacitor under fault state is critical to the safe operation of the whole driving system. This study builds the equivalent circuit of voltage source inverter (VSI) with space vector pulse width modulation (SVPWM) strategy and analyses the current characteristic of DC-link capacitance in normal operation state. The current characteristics of DC-link capacitor under main Insulation Gate Bipolar Transistor (IGBT) open-circuit fault states are analyzed and the characteristic differences from those in normal operation state are explored. Further, a fault identification method is developed. A simplified MATLAB model of EV driving system based on the VSI is established to simulate its time-domain characteristics and spectrum characteristics of DC-link capacitive current under normal operation and various fault conditions. The correctness of theoretical analysis and the effectiveness of fault identification is verified. The current spectrum characteristics of DC-link capacitance under normal operation condition are used to guide the optimal design of DC-link capacitor bank. Fault identification based on DC-link capacitor current characteristics is used to guide the fault-tolerant operation plan.
With the opening of the power distribution side and the power sales side of the power market, and the rapid increase of the number of electric vehicles (EVs) used, more and more attention has been paid to the study of EVs which are as flexible loads participating in the bidding of power market. This paper, under a certain power market environment, carries out cluster analysis according to the driving characteristics of different EV subgroups. Aiming to minimize the charging cost of the EV aggregator, considering the market clearance constraints and EVs charging load constraints, this paper establishes a two-level optimal bidding strategy model for EVs aggregator participating in the power market. According to KKT condition and dual principle, this model is transformed into mixed integer linear programming problem. An example shows that this bidding strategy of EV aggregator based on cluster characteristics can effectively reduce the charging cost of EVs.
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