链式STATCOM在零输出无功时电容电压控制方法研究

发布时间：2018-10-15 16:38

【摘要】：随着对供电可靠性以及供电质量要求的不断提高,动态无功补偿作为稳定电压水平的一种主要方法,其中静止同步补偿器具有许多优点成为目前国内外研究的热点并代表了无功补偿装置的发展趋势。链式STATCOM就是将多个H桥模块在直流输出侧串联而成,提高了电压等级,同时也增大了设备的容量。由于每个H桥之间的参数差异,使得直流侧电容电压出现不平衡现象,直接影响到装置输出电压和电流波形质量,严重时甚至会导致整个装置的崩溃。因此,链式STATCOM的直流侧电容电压平衡问题是STATCOM的研究重点和难点之一。本文分析了 STATCOM直流侧电容电压不平衡的原因以及常用的解决措施,装置正常发出无功电流时,可根据输出电流采取所需的电容电压平衡控制方法维持直流侧电容电压平衡。当装置所发出的无功电流为零或者特别小时,即零输出无功状态下,链式STATCOM采用这些电压平衡控制方法会使电压平衡能力降低,甚至失去平衡控制能力。针对该问题,本文提出了给STATCOM输出指令电流中注入三次谐波电流的方法维持直流侧电容电压平衡,分析了注入的三次谐波电流幅值与平衡可调最大功率关系,并对调控能力进行了分析,给出三次谐波电流最小幅值的确定方法,基于有功矢量叠加的平衡控制方法,在MATLAB/Simulink中搭建链式STATCOM仿真模型,仿真结果证明了所提方法的可行性。本文设计了链式STATCOM实验平台的软件程序。在该实验平台上对STATCOM零输出无功时的直流侧电容电压平衡控制方法进行了实验验证,并与传统的STATCOM直流侧电容电压控制方法进行实验对比,实验结果证明了链式STATCOM零输出无功时注入三次谐波电流维持电压平衡的有效性。
[Abstract]:With the improvement of power supply reliability and power supply quality, dynamic reactive power compensation is regarded as a main method to stabilize voltage level. Among them, static synchronous compensator has many advantages and has become a hot spot at home and abroad and represents the development trend of reactive power compensator. Chain STATCOM is a series of H-bridge modules at the DC output side, which improves the voltage level and increases the capacity of the equipment. Because of the difference of the parameters between each H bridge, the capacitance voltage on the DC side is unbalanced, which directly affects the quality of the output voltage and current waveform of the device, and even leads to the collapse of the whole device. Therefore, the DC-side capacitor voltage balance of chain STATCOM is one of the key and difficult problems in STATCOM research. In this paper, the causes of the voltage imbalance of the DC side capacitor of STATCOM and the common solutions are analyzed. When the device sends out the reactive current normally, the capacitor voltage balance of the DC side can be maintained according to the capacitive voltage balance control method required by the output current. When the reactive current emitted by the device is zero or special, that is, in the state of zero output reactive power, the chain STATCOM will reduce the voltage balance ability and even lose the balance control ability by using these voltage balance control methods. To solve this problem, a method of injecting third-harmonic current into the output instruction current of STATCOM is proposed to maintain the voltage balance of the DC side capacitance. The relationship between the amplitude of the injected third-harmonic current and the balance adjustable maximum power is analyzed. The method of determining the minimum amplitude of the third harmonic current is given. Based on the balance control method of active power vector superposition, the chain STATCOM simulation model is built in MATLAB/Simulink. The simulation results prove the feasibility of the proposed method. The software program of chain STATCOM experimental platform is designed in this paper. The DC side capacitive voltage balance control method of STATCOM with zero output reactive power is verified and compared with the traditional STATCOM DC side capacitor voltage control method. The experimental results demonstrate the effectiveness of voltage balance by injecting third-harmonic current into the chain STATCOM with zero output reactive power.
【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】：TM761.12

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