改进粒子群PI控制在三相PWM整流器中的应用

发布时间：2018-03-08 19:36

本文选题：三相VSR　切入点：电网不平衡　出处：《湘潭大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着电力电子技术的发展和科学技术的进步,用电设备对供电电源质量的要求也越来越高,三相电压型PWM整流器(三相VSR)因具备直流高压恒定输出、能量双向流动、无污染、单位功率因素运行等一系列优点被广泛应用在变流装置中。当三相PWM整流器运行在电网平衡的条件下具备良好的运行性能。然而在电力电子变流装置运行过程中,由于三相负载不平衡、单相大容量负载的使用、不对称故障等原因,不平衡现象是难以避免的。若忽略实际存在的不平衡条件,只采用传统的三相VSR控制策略,会在其网侧产生负序量,导致三相电流不平衡,造成三相VSR装置运行性能下降或不能正常运行的情况,严重时甚至烧毁装置。通常情况下,三相VSR运行时存在两方面的不平衡:一是三相电网本身存在不平衡,如相位、幅值不对称;二是三相VSR本身的参数不对称,导致系统运行不平衡。针对这一问题,本文将从不平衡条件下对三相VSR的控制策略出发,以研究改善其控制性能为目的,从以下几个方面进行论述:首先,对平衡条件下的三相电压型PWM整流器运行系统进行数学模型的建立和分析,然后给出其在三相静止abc坐标系下的数学模型转换到两相旋转dq坐标系下的过程。然后对不平衡条件下的三相VSR进行建模,分析了几种不平衡控制策略的优缺点。因提取的正、负序分量的谐波含量大小将对后续系统控制效果产生很大影响,所以选择一个好的正、负序量提取方法尤为重要。本文对比了两种不平衡条件下三相VSR正、负序量分离提取的方法(陷波器法和延时法),并分析其优缺点,选取了一种在理想状态下效果更好的方法(延时法)作为本文提取正负序量的方法。其次,本文选取了PI控制器作为调节器。PI控制器具有较强的鲁棒性、可靠性高且算法简单等优点。但在控制过程中,其参数整定过程繁杂,传统整定结果难以达到最优,最终导致控制系统性能不良,易产生超调及震荡。针对此问题,本文引入一种从平衡局部和全局搜索能力出发的改进粒子群优化算法,用于改善PI控制器的调节性能,使三相VSR达到更好的稳态性能。最后,在Matlab中首先验证了改进粒子群算法相比于原始粒子群算法的优越性;然后搭建了基于几种不平衡控制策略下三相VSR运行的仿真模型,对比应用改进粒子群PI控制器、传统PI控制器及标准粒子群PI控制器的效果,验证了应用本文所提改进粒子群PI控制器对三相VSR控制具有更好的效果。
[Abstract]:With the development of power electronic technology and the progress of science and technology, electrical equipment for power quality requirements are increasingly high, the three-phase voltage type PWM rectifier (phase VSR) with constant DC voltage output, two-way flow of energy, no pollution, a series of advantages of unit power factor operation is widely used in variable flow device. When the three-phase PWM rectifier operation has good performance in power balance condition. However, in the power electronic equipment in the process of operation, due to the unbalance of three-phase load, using single-phase large capacity load, asymmetric fault, imbalance phenomenon is difficult to avoid. If we ignore the actual existence of the unbalanced condition the use of three-phase VSR traditional control strategy can produce negative amount in the network side, resulting in unbalanced three-phase current, the operation performance of the three-phase VSR device decreased or not the normal running. Even when the serious situation, burn the device. Typically, the VSR runtime three-phase imbalance exists in two aspects: one is the three-phase power grid itself is not balanced, such as phase and amplitude asymmetry; two parameters of asymmetric three-phase VSR itself, so that the system operation is not balanced. In order to solve this problem, this paper will be the starting control strategy of VSR never three-phase equilibrium conditions, to improve the control performance for the purpose of research, discusses from the following aspects: firstly, the establishment and analysis of three-phase voltage type PWM rectifier system under equilibrium conditions of the mathematical model, and then gives the conversion in three-phase ABC coordinate system of the mathematical model of the two-phase process the rotating dq coordinate system. Then the modeling of three phase unbalance under the condition of VSR, analyses the advantages and disadvantages of unbalanced control strategy. Because the extraction of positive and negative sequence components of the harmonic content of size To follow the effect of control system have a great impact, so choose a good positive and negative sequence extraction method is particularly important. This paper compares two kinds of unbalanced conditions of three-phase VSR positive and negative sequence separation method (notch filter and delay method), and analyze its advantages and disadvantages, select a a method is better in ideal condition (delay method) as the extraction method of positive and negative sequence quantities. Secondly, this paper selects the PI controller as the regulator.PI controller has strong robustness, high reliability and simple algorithm. But in the control process, the parameter tuning process is complicated, the traditional setting it is difficult to achieve optimal results, resulting in poor performance of control system, easy to overshoot and oscillation. To solve this problem, this paper introduces a modified particle starting from the balance of local and global search ability of the swarm optimization algorithm was used to improve the PI controller Adjusting performance and steady-state performance of the three-phase VSR achieve better. Finally, first in the Matlab to verify the superiority of the improved particle swarm algorithm compared to the original particle swarm algorithm; and then build the simulation model of three-phase unbalance control based on VSR operation strategy under several contrast application of improved particle swarm optimization PI controller, PI controller and traditional standard particle swarm optimization PI controller, verify the application of the proposed improved particle swarm PI controller has better control effect on the three-phase VSR.

【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP18;TM461

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