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1.
福建省体育馆工程是建设部重点实施技术示范工程,在施工中结合工程施工特点和创优目标,研究、开发、应用了四大类共10余项重点实施新技术,完成了推新任务和创优的目标。 相似文献
2.
对同步电机启动、加速、励磁模式切换等工作过程中变频器的应用进行了论述,介绍了电网改造的经济方案,提出了变频器在使用时的注意事项,达到既要节能又要省费用的电网改造效果。 相似文献
3.
由于定子直接连接到电网,电网电压中的负序和谐波分量会严重恶化双馈风力发电机(DFIG)系统的运行性能,导致系统输出总电流三相不对称及谐波畸变、总输出有功功率及无功功率波动等,使得DFIG系统无法安全稳定可靠运行,且输出风电质量下降。同时考虑负序和谐波电网下DFIG系统机侧变流器和网侧变流器的运行状态,以改善DFIG系统总输出电流或功率质量为目标,研究基于二阶矢量积分器(SOVI)的DFIG系统网侧和机侧变流器改进直接功率控制(DPC)策略,改善DFIG系统的运行性能。实验结果验证了所提出的负序和谐波畸变电网电压下DPC策略的正确性及有效性。 相似文献
4.
This paper presents an optimal coordinated voltage control scheme for preserving long-term voltage stability of power systems. Linear quadratic integral (LQI) controller is employed to construct this scheme. Also, this paper considers the detailed dynamic model of doubly-fed induction generator (DFIG) wind turbine, synchronous generators, over excitation limiter (OEL) and under-load tap changer (ULTC) system, which are important elements influencing voltage stability of power systems. The proposed approach at each time instance involves following two major steps: First, the power system nonlinear equations are linearized and optimal controllers are obtained by LQI technique. Then, in the second step the system dynamic behavior is investigated via time-domain simulations by applying the attained optimal control signals at the first step. The impact of the proposed coordinated voltage control scheme is evaluated by time domain simulations on a well-known test system, under variable wind speed and fault conditions. 相似文献
5.
Emad Gameil Shehata 《电力部件与系统》2017,45(11):1231-1241
Despite its several advantages, a classic direct power control (DPC) technique of doubly fed induction generators (DFIGs) driven by variable-speed wind turbines has some drawbacks such as high power ripples and variable switching frequency. In this paper, two robust controllers are designed to improve the classical DPC performance without complicating the overall scheme. First, an integral sliding mode controller (ISMC) is designed to regulate the stator active and reactive powers. Two integral switching functions are selected for controlling stator active and reactive powers. The idea of total sliding mode controller is selected to avoid reaching phase stability problem. Second, a diagonal recurrent neural network (DRNN) controller is designed and trained based on DPC. The DRNN has several advantages compared to the classical static neural networks such as recurrence and simple construction. Simple off-line back-propagation algorithm is proposed to train the proposed DRNN. The stability of the proposed ISMC and DRNN controller is proved using the Lyapunov stability theorem. The grid side converter is controlled based on the DPC principle to ensure both constant DC-link voltage and grid side reactive power. The feasibility of the proposed DPC schemes is validated by simulation studies on a 1.5-MW wind power generation system. The performance of the proposed schemes is compared with a conventional DPC scheme under different operating conditions. 相似文献
6.
Hyoung‐Woo Kim Hongju Kim Soonman Kwon Joon‐Young Choi 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(5):633-639
A robust backstepping controller with nonlinear damping is designed for the grid‐side converter (GSC) of a grid‐connected doubly fed induction generator (DFIG) in wind energy conversion systems (WECSs). The designed controller achieves the exponential ultimate boundedness of both the DC‐link voltage and GSC current errors with an arbitrarily fast decay rate and an arbitrarily small bound in the presence of both model uncertainties and time‐varying external disturbances. A desirable feature that distinguishes the proposed controller from other existing controllers is that the control input of GSC is constructed only by the static feedback of the measurable states. As a result, the control input becomes smooth and easy to implement without requiring differentiation or switching operations. The exponential boundedness and performance of the designed controller are demonstrated by simulation using a 1.5‐MW DFIG‐based WECS model built in MATLAB/SimPowerSystems and compared with a standard proportional‐integral controller. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
7.
8.
Abstract—This article presents the design of optimal output feedback automatic generation control regulators for an interconnected power system with dynamic participation of doubly fed induction generator based wind turbines. The power systems consist of plants with hydro-thermal turbines and are interconnected via parallel AC/DC links. Efforts have been made to propose optimal automatic generation control regulators based on feedback of output state variables, which are easily accessible and available for the measurement. The designed optimal output feedback automatic generation control regulators are implemented, and the system dynamic responses for various system states are obtained considering 1% load perturbation in one of the areas. The dynamic performance is compared with that obtained with optimal automatic generation control regulators designed using full state vector feedback. The pattern of closed-loop eigenvalues is also determined to test the system stability. 相似文献
9.
考虑风电功率预测的分散式风电场无功控制策略 总被引:3,自引:1,他引:2
分散式风电接网模式可以解决集中式并网限电等问题,但对配电网传统运行模式带来挑战。为解决其经济稳定运行难题,提出了一种包含无功预测、无功整定、无功分配的三层新型分散式风电场无功协调控制策略。其中,无功预测层利用物理和统计方法组合预测单台机组未来无功输出能力;无功整定层针对有无无功补偿设备,提出风电机组基于电网无功缺额降出力的自身补偿和多时间尺度协调离散补偿设备、静止无功发生器(SVG)与风电机组共同补偿配电网无功需求方法;无功分配层基于风电功率预测无功功率信息,考虑风速波动性,按照优先级动态筛选风电机组,调节其输出功率以跟踪无功补偿指令。工程算例证明了所提策略可以有效提高电压支撑能力,减小风电场损耗。 相似文献
10.
《Journal of Nuclear Science and Technology》2013,50(8):317-325
Electrical conductivity and X-ray diffraction studies on non-stoichiometric U3O8-x phase were carried out simultaneously in the range 765°≦T≦995°C and 10?4≦Po2≦1 atm. The plot of logσ vs. logPo2 showed many refractions which corresponded with the phase transitions determined by thermogravimetry reported in the preceding paper. Based on the data of both electrical conductivity and thermogravimetry, the non-stoichiometric defect structures of various U3O8-x phases are interpreted as consisting of singly charged oxygen interstitials (Ol′) and doubly charged oxygen vacancies (Vo.)? Some of the X-ray diffraction lines were found to undergo splitting with decreasing oxygen partial pressure. These splits are qualitatively discussed in reference to the out-of-step structure model. The mechanism of electrical conduction in the high temperature hexagonal U3O8-x phases is surmised to be the hopping of small polarons. 相似文献