Advances in Mechanics Engineering

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Authors: Shao Bo Li, Lin Chuan Li, Lei Zhang, Qian Sun
Abstract: Wind turbine absorbs reactive power while generating active power. Seriously, it causes voltage drop or even voltage collapse. It is needed to compensate reactive power. In this paper, a combination of capacitor bank and SVC is used in wind farm. Equivalent circuit of two kinds of wind turbine is described firstly. Then, equation of reactive power and active power is derived. Then an optimization method is used to calculate capacity of capacitor bank and SVC. Finally, load flow of IEEE14 system with a wind farm connected to it is calculated to verify the effect of reactive power compensation.
563
Authors: Ge Fei Qiu, Zheng Lin, Li Jun He, Jun Hao Cao, Xiao Dan
Abstract: Based on the analysis of damping theory of Thyristor Controlled Series Capacitor (TCSC), the influence of TCSC to electric magnetic torque with and without damping function is studied by one generator infinite model so to deduce the mechanism of low frequency oscillation damping of TCSC. Combined with ‘the Twelfth Five-year Plan’ power and transmission grid construction plan in western Yunnan, the proper scheme for TCSC damping control was chosen in the southwestern Yunnan power grid and the transient and dynamic simulations of southwestern Yunnan power grid were performed. The simulation results show that TCSC can improve the system damping when the grid is in Yunguang area oscillation mode with frequency of 0.27Hz and 0.6Hz,especially in condition when Yunnan grid is in the local area oscillation mode of 0.6 Hz. The simulations also demonstrate that TCSC can improve transient stability of Yunnan power grid. The application of TCSC in southwestern Yunnan Power Grid is of great significance to power grid safe operation.
567
Authors: Yan Juan Wu, Lin Chuan Li
Abstract: Some faults will result wind turbine generators off-grid due to low grid voltage , furthermore, large-scale wind farms tripping can result in severe system oscillation and aggravate system transient instability . In view of this, static compensator (STATCOM) is installed in the grid containing large-scale wind farm. A voltage feedforward control strategy is proposed to adjust the reactive power of STATCOM compensation and ensure that the grid voltage is quickly restored to a safe range. The mathematical model of the doubly-fed induction wind generator (DFIG) is proposed. The control strategy of DFIG uses PI control for rotor angular velocity and active power. 4-machine system simulation results show that the STATCOM reactive power compensation significantly improve output active power of large-scale wind farm satisfying transient stability, reduce the probability of the tripping, and improve the utilization efficiency of wind farms.
574
Authors: Shi Cai Fan, Wen Ru Li, Tao Peng
Abstract: As the core component of wind turbine generator system, the quality of wind power converter attracts great attention. Traditionally, manual testing has been the way to ensure the board performance. Based on virtual instrument, a hardware-in-the-loop test platform is designed using the LabVIEW graphical programming language. A method based on FFT spectrum analysis shows high precision in detection the phase shift of current signals, which would outperform the zero-crossing method when noises could not be omitted; and a method based on BP neural network improves the calibration precision of temperature detection channels. The satisfying precision and efficiency in application show great advantage in many aspects compared to the traditional testing method.
578
Authors: Yu Xin Wang, Feng Ge Zhang, Xiao Ju Yin, Shi Lu Zhu
Abstract: A derivation calculation methods for the maximum power point tracking is proposed in this paper. This method is the direct calculation method for the maximum power point tracking, through the calculation of the derivative value of the power to voltage, adjust the change values of occupies emptiescompared, which is used to deduce the voltage and current value, judge whether the derivative of the power to the voltage is zero, if it is ture, the maximum power point is got. Hardware is used the method to regulate the duty ratio of PWM in DC/DC boost circuit ,though once sampling, it can calculate the value of voltage and the duty ratio at maximum power point. The prototype experiments using DSP2812 chip verify that the inverter can better realize the most power tracing, high accuracy, and the system has the high stability.
583
Authors: Lan Xin Hu, Cheng Hua Cai, Xia Fen Tian, Ying Fan, Jian Hao Jia, Chun Lei Wei
Abstract: In this paper, the wind power generation monitoring system hardware research, design a real-time monitoring the operation of the air handling unit, based on wireless sensor network. Use of wireless sensor networks to collect relevant data, data analysis and processing of the MCU as the core components, combined with a GSM module, Zigbee module for wireless transmission of data to achieve the purpose of real-time monitoring.
587
Authors: Xia Li
Abstract: This article gives the description of the scheme of solar lighting control system. Solar energy is accepted commonly as a green energy because of its unique advantages. In the strong support of the government, the Photovoltaic (PV) generation system gains a rapid development. The stand-alone and grid-connected PV generation systems will be the trend among PV applications. Based on the solar lighting control system, the scheme includes using intelligent control to complete charging and discharging to prevent the battery from being over-charged and over-discharged. Meanwhile the constant current technology is used to drive LED, and the integrated circuit technology is used to implement the solar energy lighting optically controlled self extinguishing.
591
Authors: Lei An Zhang, Xue Mei Huang, Xiu Ting Wei
Abstract: According to MW-class wind turbine blades loading system requirements, the load requirement of traction apparatus under the different operating conditions were discussed. At the same time, the variable traction feature of traction apparatus was analyzed. A multi-node hydraulic loading system based on CAN bus was designed in this paper. In order to improve the precision of traction and the following performance of loading system, opting for the “V-F” control mode, we proposed the variable proportional separate integral control algorithm with amplitude limit to enhance the system's adaptive capacity. Experiments show that this program has a good coordination feature in the variable traction control, and fully meets the requirements of blade loading test.
595
Authors: Bao Cheng Wang, Gu Yong Han, Song Lu, Jun Zhou
Abstract: According to the internal specific equipment and facilities in the automatic charging station, with the actual lightning distribution in the automatic charging station, the modern way of lightning protection and the scientific design principle and design thought, we put the lightning protection engineering in the automatic charging station into five parts: the lightning protection of buildings, the lightning protection of power system, the lightning protection of lights monitoring system, the equipotential connection, the common grounding system and indoor shielding. With the characteristics of each part, we design the lightning protection. At last, we use the common ground system to connect with each part of the organic, then forming a comprehensive lightning protection system, so as to ensure the safety of the automatic charging station lightning protection.
599
Authors: Ya Mei Yu, Run Sheng Tang, Chao Feng Xia
Abstract: In this work, irradiation distribution on the base of ideal two-dimensional CPCs with and without a restricted exit angle, to which solar cells are attached, are analyzed by the ray-tracing technique. Results show that, given an acceptance half-angle (Θa), for CPCs without a restricted exit angle (CPC-1), radiation flux distribution on the base depends on the incidence angle of solar rays (Θ ); whereas for CPCs with a restricted exit angle (CPC-2), the flux distribution depends on and the restricted exit angle (Θe). For both CPC-1 and 2 with identical geometric concentration factor (Ct=2) and acceptance half-angle ( Θa=20), the peak flux concentration ratio on the base of CPC-2 with =65o decreases about 43%, 30% and 49% for the radiation at the incident angle of 0o, 10o and 18o, respectively, as compared to CPC-1. This implies that solar flux distribution on the base of CPC-2 is more uniform, thus, more efficient for photovoltaic conversion as compared with CPC-1.
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