基于TTA检测算法的三相负荷不平衡治理研究

发布时间：2018-08-20 19:04

【摘要】：各种非线性负荷及大容量单相负荷的接入,使配电变压器长期处于不平衡运行状态,严重危及了电力系统的安全稳定运行。不平衡调补装置是治理不平衡现象的有效手段,其中补偿电流检测算法是影响调补装置补偿性能的关键技术之一。本文主要针对三相四线制不平衡负载条件下的基波负序及零序电流检测算法进行研究。针对上述问题,对基于时域变换的电流检测算法(TTA)进行详细分析,结果表明:当电网电压三相对称时,TTA算法能准确检测出负载中的不平衡分量。但是,当电网电压不对称时,由于锁相环不准确锁相会产生检测误差,导致检测到的不平衡电流分量存在误差。为减小TTA电流检测算法在电网电压不对称时由于锁相不准确造成的误差,采用由二阶广义积分器(SOGI)和电压正序提取环节相结合的锁相环(SOGI-PLL)。仿真验证了由SOGI-PLL和TTA相结合的电流检测能有效提高传统TTA检测算法的精度。此外,为提高电流检测环节中滤波器的动态响应速度,采用二阶低通滤波器和带阻滤波器串联组合的方式进行滤波,在不影响检测精度的情况下大幅提高了检测算法的动态响应速度。借助Matlab/Simulink搭建了三相四线制调补系统仿真模型,分别在三相电网电压对称和不对称情况下进行了仿真分析,仿真结果表明,在上述两种情况下研究的基于广义积分器的TTA电流检测算法均能快速准确地对负载电流中的负序及零序分量进行提取,达到了预期效果。在此基础上,在现场实际系统中进行应用,进一步验证了该算法的可行性和实用性。
[Abstract]:All kinds of nonlinear load and large capacity single-phase load connection make the distribution transformer in unbalanced operation state for a long time which seriously endangers the safe and stable operation of power system. The unbalanced adjusting and compensating device is an effective means to control the unbalanced phenomenon, and the compensation current detection algorithm is one of the key technologies that affect the compensation performance of the compensation device. In this paper, the detection algorithms of fundamental negative sequence and zero sequence current under three phase four wire unbalanced load are studied. To solve the above problems, the current detection algorithm based on time-domain transform (TTA) is analyzed in detail. The results show that the proposed algorithm can accurately detect the unbalanced components in the load when the three-phase voltage is symmetrical. However, when the voltage of the power system is asymmetric, there is an error in the detection of the unbalanced current component due to the phase locked loop (PLL) inaccurate phase locking error. In order to reduce the error caused by phase locking in TTA current detection algorithm when the voltage is asymmetric, a phase-locked loop (SOGI-PLL), which is combined with the second-order generalized integrator (SOGI) and the voltage positive sequence extraction link, is adopted. Simulation results show that the current detection combined with SOGI-PLL and TTA can effectively improve the accuracy of the traditional TTA detection algorithm. In addition, in order to improve the dynamic response speed of the filter in current detection, the second-order low-pass filter and band-stop filter are combined in series to filter. The dynamic response speed of the detection algorithm is greatly improved without affecting the detection accuracy. With the help of Matlab/Simulink, the simulation model of three-phase four-wire system is built, and the simulation analysis is carried out under the condition of voltage symmetry and asymmetry of three-phase power network, respectively. The simulation results show that, In both cases, the TTA current detection algorithm based on the generalized integrator can extract the negative sequence and zero sequence components of the load current quickly and accurately, and achieve the desired results. On this basis, the algorithm is applied in the field system, and the feasibility and practicability of the algorithm are further verified.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM732

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