低压配网三相负荷自平衡装置及其控制策略

发布时间：2018-02-24 15:25

本文关键词： 静止换相开关自平衡控制三相不平衡电能质量　出处：《西安理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国低压配网属于三相四线制系统,大量使用着单相负荷,导致配网内单相负荷在三相间分配严重不平衡,尤其是居民小区和商住建筑配电系统。三相负荷不平衡会引起零线电流过大、电网损耗过高、三相电压不平衡、电网电压低下、三相电力设备利用率低、中性线电位升高危及人身安全等问题。三相负荷不平衡已成为低压配网急需解决的难题之一。针对单相负荷在三相中的分配不均以及单相负荷使用上的随机性,本文提出了一种基于电力电子技术的三相负荷自平衡装置及其自适应平衡控制策略。自平衡装置由多台静止换相开关和一套控制装置组成,控制装置通过监测三相平衡状态和分析计算,决策单相负荷的最佳换相方案,并控制相应的静止换相开关自动实施换相,达到三相系统的最佳平衡状态。所完成的研究工作主要包括:设计了一种单相负荷静止换相开关。它是一种采用晶闸管过零投切技术的智能化静止开关,接收来自上位机的通信控制命令,以实现单相负荷在三相中平稳、无冲击地任意切换。通过理论分析和仿真验证,提出了静止开关由当前相切换到超前相或切换到滞后相的最佳投切时刻与投切策略,确保开关相间切换的安全性和单相负荷断电时间最短。设计了三相负荷自平衡装置的控制装置,设计了自适应平衡策略。控制装置采集各单相负荷的电流及其当前所在相序,分析三相电流的不平衡度,通过负荷平衡优化策略确定单相负荷的最佳调整方案,对相应的静止换相开关发出换相指令。为了避免开关的频繁切换,控制策略中引入了基于负荷历史数据的负荷预测机制。建立了三相负荷自平衡装置的仿真模型,验证了三相负荷自适应平衡策略的有效性。开发了静止换相开关和自平衡装置的控制系统,设计了原理线路,编制了应用程序,开展了相关实验。仿真和实验结果表明了三相负荷自平衡装置及其控制策略的正确有效性。
[Abstract]:The low-voltage distribution network in China belongs to three-phase four-wire system, and the single-phase load is widely used, which leads to the serious imbalance of the distribution of single-phase load among the three phases in the distribution network. Especially in residential areas and commercial and residential buildings and distribution systems, three-phase load imbalance will cause excessive zero line current, high grid loss, unbalanced three-phase voltage, low grid voltage, low utilization rate of three-phase power equipment, The unbalance of three-phase load has become one of the problems that need to be solved in low-voltage distribution network. In view of the uneven distribution of single-phase load in three-phase and the randomness of single-phase load, In this paper, a three-phase load self-balancing device based on power electronics technology and its adaptive balancing control strategy are proposed. The self-balancing device consists of several static commutation switches and a set of control devices. By monitoring the state of three-phase balance and analyzing and calculating, the control device makes decision on the optimal commutation scheme of single-phase load, and controls the corresponding static commutation switch to implement commutation automatically. In order to achieve the optimal balance state of the three-phase system, the research work accomplished mainly includes the design of a single-phase load static commutation switch, which is an intelligent static switch using thyristor zero-crossing switching technology. Receiving the communication control command from the upper computer to realize the single-phase load switching smoothly and arbitrarily without impact in the three-phase. Through theoretical analysis and simulation, The optimal switching time and switching strategy for the static switch from the current phase to the leading phase or to the hysteresis phase are proposed. The security of switch phase switching and the shortest time of single phase load outage are ensured. The control device of three-phase load self-balancing device and the adaptive balancing strategy are designed. The control device collects the current of each single-phase load and its current phase sequence. The unbalance degree of three-phase current is analyzed, the optimal adjustment scheme of single-phase load is determined by load balance optimization strategy, and the commutation instruction is given to the corresponding static commutation switch. The load forecasting mechanism based on load history data is introduced in the control strategy, and the simulation model of three-phase load self-balancing device is established. The control system of static commutation switch and self-balancing device is developed, the principle circuit is designed, and the application program is programmed. The simulation and experimental results show that the three-phase load self-balancing device and its control strategy are correct and effective.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761

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