In this paper, a new inductive filtering scheme with a four-winding inductive filtering converter transformer (FWIFCT) and its filtering system is proposed to solve the harmonic pollution problems generally existing i...
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In the early fault period of high-speed train systems, the interested characteristic signals are relatively weak and easily submerged in heavy noise. In order to solve this problem, a state-transition-algorithm (STA)-...
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In the early fault period of high-speed train systems, the interested characteristic signals are relatively weak and easily submerged in heavy noise. In order to solve this problem, a state-transition-algorithm (STA)-based adaptive stochastic resonance (SR) method is proposed, which provides an alternative solution to the problem that the traditional SR has fixed parameters or optimizes only a single parameter and ignores the interaction between parameters. To be specific, the frequency-shifted and re-scaling are firstly used to pre-process an actual large signal to meet the requirement of the adiabatic approximate small parameter. And then, the signal-to-noise ratio is used as the optimization target, and the STA-based adaptive SR is used to synchronously optimize the system parameters. Finally, the optimal extraction and frequency recovery of a weak characteristic signal from a broken rotor bar fault are realized. The proposed method is compared with the existing methods by the early broken rotor bar experiments of traction motor. Experiment results show that the proposed method is better than the other methods in extracting weak signals, and the validity of this method is verified.
In this paper, the mathematical model of reactive power optimization is established by using objective function, in order to minimize the sum of power loss and investment cost of newly added reactive power compensatio...
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ISBN:
(数字)9781728146539
ISBN:
(纸本)9781728146546
In this paper, the mathematical model of reactive power optimization is established by using objective function, in order to minimize the sum of power loss and investment cost of newly added reactive power compensation equipment, and an improved particle swarm optimization algorithm based on bacterial chemotaxis was proposed to solve the model. The algorithm takes particle swarm optimization algorithm as the standard, uses chaotic sequence to initialize the population, to improve the diversity of initial population, change the inertia weight and learning factor by using cosine nonlinear transformation, and enhance the global search and learning ability of particles, improves the accuracy of the algorithm, maintains the population diversity through bacterial chemotaxis, and improves the convergence stability of the algorithm. The simulation results in IEEE 30-bus system verify the effectiveness of the improved PSO algorithm in solving the reactive power optimization problem of distribution network.
In order to detect electro-osmosis flow conveniently, a digital small-power high-voltage DC (HDC) power supply based on DSP is introduced which is fully controllable and fast response. The structure of the main circui...
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ISBN:
(数字)9781728146539
ISBN:
(纸本)9781728146546
In order to detect electro-osmosis flow conveniently, a digital small-power high-voltage DC (HDC) power supply based on DSP is introduced which is fully controllable and fast response. The structure of the main circuit is Buck converter which is controlled by the voltage PWM control technology. A voltage feedback closed loop is used in the circuit, in which the digital optical fiber is used for isolation and transmission. Addition to data collection, the DSP controller calculates the duty cycle, which is based on the feedback signal, so that the output voltage can be real-timely traced and monitored. Consequently, the principle of whole system including control circuit and main circuit is described. Finally, the feasibility of the proposed approach is verified on a simulink model with 220V input and 4000V/1mA output. The results show that the HDC system meets the need of automatically detect electroosmosis experiment and gives full play to the convenience of digital power and control.
With growing concerns about renewable energy consumption, pumped storage power plant is becoming a popular concept and thus the modeling of the doubly fed generator based hydrogeneration system becomes an interesting ...
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With growing concerns about renewable energy consumption, pumped storage power plant is becoming a popular concept and thus the modeling of the doubly fed generator based hydrogeneration system becomes an interesting ...
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ISBN:
(数字)9781728131375
ISBN:
(纸本)9781728131382
With growing concerns about renewable energy consumption, pumped storage power plant is becoming a popular concept and thus the modeling of the doubly fed generator based hydrogeneration system becomes an interesting research topic. In this paper the powercontrol strategy on the doubly fed generator based on pumped storage power plant with the aim of active power and slip control was studied. multi-index control was employed to achieve the independent control of active power and slip of the machine. The machine was modeled in state equations in a synchronous reference frame. The complete simulation model was developed for such hydrogeneration system under variable speed operation using MATLAB & Simulink environment for obtaining the optimal parameters of multi-index control and the dynamic performance got further improved.
Novel hybrid refill friction stir spot welding （RFSSW） assisted with ultrasonic oscillation was introduced to 5A06 aluminum alloy joints. The metallographic structure and mechanical properties of 5A06 aluminum alloy...
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Novel hybrid refill friction stir spot welding （RFSSW） assisted with ultrasonic oscillation was introduced to 5A06 aluminum alloy joints. The metallographic structure and mechanical properties of 5A06 aluminum alloy RFSSW joints formed without ultrasonic assistance and with lateral and longitudinal ultrasonic assistance were compared, and the ultrasonic-assisted RFSSW process parameters were opti- mized. The results show that compared with lateral ultrasonic oscillation, longitudinal ultrasonic oscillation strengthens the horizontal bond- ing ligament in the joint and has a stronger effect on the joint＇s shear strength. By contrast, lateral ultrasonic oscillation strengthens the ver- tical bonding ligament and is more effective in increasing the joint＇s tensile strength. The maximum shear strength of ultrasonic-assisted RFSSW 5A06 aluminum alloy joints is as high as 8761 N, and the maximum tensile strength is 3679 N when the joints are formed at a tool rotating speed of 2000 r/rain, a welding time of 3.5 s, a penetration depth of 0.2 mm, and an axial pressure of 11 kN.
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