电网不平衡下锁相环技术的研究

发布时间：2018-02-27 01:01

本文关键词： 故障穿越电网不平衡锁相环双dq旋转坐标系双二阶广义积分器　出处：《大连海事大学》2017年硕士论文　论文类型：学位论文

【摘要】：现代电网规范要求双馈风电系统必须具备故障穿越运行的能力。电网故障下双馈风电系统的故障穿越运行能力是决定双馈风电系统能否并入电网的重要因素。故障穿越运行的重要技术之一——电网不平衡下的锁相环技术,为双馈风电系统的转子侧和网侧变流器提供控制基准,对双馈风电系统在故障电网下的并网运行有着重要的作用。本文对电网不平衡下的锁相环技术进行了深入研究。首先,在分析同步坐标系锁相环的组成结构和数学模型的基础上,详细研究了同步坐标系锁相环在电网电压幅值不平衡、电网存在谐波及存在直流偏置电压三种情况下的动静态性能,并对相应情况下的误差进行了分析。其次,介绍了适用于电网不平衡下的正负序双dq旋转坐标系锁相环和双二阶广义积分器锁频环的工作原理。针对正负序双dq旋转坐标系锁相环在电网存在直流偏置电压下检测结果误差较大的问题,将静止坐标系锁相环的鉴相器环节加入到正负序双dq旋转坐标系锁相环的结构中,改进了正负序双dq旋转坐标系锁相环的拓扑结构;针对双二阶广义积分器锁频环在电网存在直流偏置电压下不能准确检测电网频率和相位的问题,将直流电压的负反馈环节加入到移相积分器的结构中,改进了双二阶广义积分器锁频环的拓扑结构。最后,搭建同步坐标系锁相环、正负序双dq旋转坐标系锁相环、改进型正负序双dq旋转坐标系锁相环、双二阶广义积分器锁频环、改进型双二阶广义积分器锁频环的仿真模型,对仿真结果进行了对比分析;在此基础上,设计完成了锁相环实验系统硬件平台,并对电网不平衡下锁相环技术进行实验验证。仿真和实验结果验证了理论分析的正确性。
[Abstract]:The modern grid specification requires that the doubly-fed wind power system must have the ability of fault traversing operation. The fault traversing ability of the doubly-fed wind power system is an important factor determining whether the doubly-fed wind power system can be incorporated into the power network. One of the most important technologies for obstacle traversing operation is the phase-locked loop (PLL) technology under unbalanced power grid. This paper provides control datum for rotor side and grid side converter of doubly-fed wind power system, and plays an important role in grid-connected operation of doubly-fed wind power system under fault grid. In this paper, the phase-locked loop technology in unbalanced power grid is deeply studied. On the basis of analyzing the structure and mathematical model of PLL in synchronous coordinate system, the dynamic and dynamic performance of PLL in synchronous coordinate system under the condition of unbalanced voltage amplitude, harmonic and DC bias voltage is studied in detail. The error of the corresponding case is analyzed. Secondly, This paper introduces the working principle of positive and negative sequence double dq rotation coordinate system phase-locked loop and double second order generalized integrator frequency locking loop under unbalanced power network. There exists DC bias voltage for positive and negative sequence double dq rotation coordinate phase locked loop in power network. The problem that the error of the test result is large, The phase detector of the stationary coordinate system phase locked loop is added to the structure of the positive and negative sequence double dq rotation coordinate system, and the topology of the positive and negative order double dq rotation phase locked loop is improved. In order to solve the problem that the frequency locking loop of double second order generalized integrator can not accurately detect the frequency and phase of power network under DC bias voltage, the negative feedback link of DC voltage is added to the structure of phase shift integrator. The topology of frequency locking loop of double second order generalized integrator is improved. Finally, a phase locked loop in synchronous coordinate system, a phase locked loop in positive and negative order double dq rotation coordinate system, an improved phase locked loop in positive and negative order double dq rotation coordinate system and a frequency lock loop in double second order generalized integrator are built. The simulation model of the improved double second order generalized integrator frequency locking loop is compared and analyzed, and the hardware platform of the phase locked loop experimental system is designed. The simulation and experimental results verify the correctness of the theoretical analysis.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614;TM732

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