低压配电网不平衡调补装置控制系统研究

发布时间：2019-03-21 10:12

【摘要】：低压配电网各种单相负荷及三相不对称负荷大量接入,尤其在三相四线制系统中,三相低压配电网不平衡问题日益凸显,对低压电网安全运行带来严重影响,电网不平衡运行的治理显得尤为重要。采用三相四桥臂电力电子变流器构成的不平衡调补装置是解决此问题的有效措施之一。主要研究内容如下:(1)分析了适用于三相四线制系统常用的几种变流器拓扑结构,采用三相四桥臂变流器加单电感并网接口为不平衡调补装置主拓扑。通过检测低压配电网负荷电流中非正序分量,并由装置向电网注入相反分量,来实现不平衡电流治理。(2)采用基于广义二阶积分的FBD法检测电流非正序分量,为提高检测精度和动态响应速度,采用陷波器和宽频带低通滤波器组合滤波。(3)以αβγ坐标系下三相四桥臂调补装置的数学模型为基础,设计了基于PI控制器和准PR控制器的电压电流双闭环控制系统。通过理论分析,所设计控制系统具有良好的稳态性能和动态性能。采用abc坐标系下的三维空间矢量调制算法,有效提高了变流器直流侧电压利用率,改善了变流器输出电流波形。在simulink环境下搭建不平衡调补装置仿真模型,分别在电网电压对称和不对称情况下对系统控制性能进行分析和验证。仿真结果表明,改进的电流检测算法具有良好的动态性能,三相负荷不平衡治理效果良好,所设计三相负荷不平衡治理方案合理。根据设计原理搭建了三相负荷不平衡调补装置硬件系统。
[Abstract]:A large number of single-phase loads and three-phase asymmetrical loads are connected in low-voltage distribution network. Especially in the three-phase four-wire system, the unbalanced problem of three-phase low-voltage distribution network is becoming increasingly prominent, which has brought serious impact on the safe operation of the low-voltage power network. The management of unbalanced operation of power grid is very important. One of the effective measures to solve this problem is to adopt unbalanced compensator composed of three-phase four-leg power electronic converter. The main contents are as follows: (1) the topology of three-phase four-wire converter is analyzed. The main topology of unbalanced regulator is three-phase four-leg converter and single inductance grid-connected interface. By detecting the non-positive sequence component in the load current of low-voltage distribution network, and injecting the opposite component into the power network by the device, the unbalanced current can be eliminated. (2) the FBD method based on generalized second-order integral is used to detect the non-positive sequence component of the current. In order to improve the detection accuracy and dynamic response speed, a notch filter and a wide band low-pass filter are used. (3) based on the mathematical model of the three-phase four-leg tuning device in 伪尾纬 coordinate system, A voltage-current double closed-loop control system based on PI controller and quasi-PR controller is designed. Through theoretical analysis, the designed control system has good steady-state performance and dynamic performance. The three-dimensional space vector modulation algorithm in abc coordinate system is used to effectively improve the DC side voltage utilization ratio and the output current waveform of the converter. The simulation model of unbalanced regulator is built in simulink environment, and the control performance of the system is analyzed and verified under the condition of symmetrical and asymmetric grid voltage respectively. The simulation results show that the improved current detection algorithm has good dynamic performance, the three-phase load imbalance control effect is good, and the designed three-phase load imbalance control scheme is reasonable. According to the design principle, the hardware system of three-phase unbalanced load adjusting and compensating device is built.
【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】：TM761.12

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