电容式电压互感器速饱和阻尼器优化计算模型研究

发布时间：2019-04-15 18:25

【摘要】：电容式电压互感器(Capacitor Voltage Transformer,CVT),是电力系统110kV及以上电压等级中的重要电气设备。由于CVT主要由电容与非线性电感元件构成,在暂态情况下容易激发自身的分次谐波铁磁谐振,目前,抑制CVT铁磁谐振的主要方法是在CVT二次侧加装阻尼器,因为速饱和阻尼器性能优良,阻尼特性好,在CVT阻尼器中得到普遍应用。阻尼器电阻值的大小对于阻尼器的阻尼效果起着至关重要的作用。但目前,对于速饱和阻尼器电阻值选择的研究甚少,仅能通过一些公式计算出阻尼电阻值一个很大的上限范围。此外由于计算模型简单,结果与工程实际情况往往偏差很大。因此,在工程中,一般通过大量的铁磁谐振试验来最终确定CVT所需的最佳阻尼电阻值,这种方法工作量大,造成了很大的人力、物力上的浪费。另外基于电磁暂态计算软件ATP-EMTP建立CVT铁磁谐振仿真模型的研究,虽然提高了阻尼电阻选择的的准确性,但计算量非常大,且需要各元件的准确参数。根据铁磁谐振现象和电路振荡条件,本文建立了CVT速饱和阻尼器的阻尼电阻值选择的优化计算模型。按照CVT的等值电路,首先建立CVT等值电路的回路方程,然后利用该方程推导出了阻尼电阻达到阻尼条件,必须满足的一元三次常系数偏微分方程。通过求解该数学方程,得到了CVT铁磁谐振的阻尼条件。根据该条件可以较容易地计算出各分次谐波下阻尼电阻的取值范围,可将阻尼电阻值限定在一个很小的范围内。利用该计算模型,对江苏无锡日新厂两台CVT产品进行了计算,对比后发现,该模型计算出的阻尼电阻非常接近工程选用电阻。证明了计算模型的正确性和可行性。本文方法计算量小,可用于指导工程设计。为了充分论证优化计算模型的正确性,本文又分别采用了建模仿真和现场实验的方法,对本文CVT速饱和阻尼器阻尼电阻选择优化模型计算出的阻尼电阻值的范围进行验证。在软件仿真方面,运用EMTP-ATP软件建立CVT仿真模型,对计算模型确定的阻尼电阻值范围分别进行了铁磁谐振仿真;在实验验证方面,选取由计算模型确定的范围中的多个阻尼电阻值分别进行铁磁谐振实验。仿真和实验的结果均表明通过该优化计算模型选取的电阻值可有效地阻尼铁磁谐振,证明了该模型能够很好的解决CVT阻尼器阻尼电阻的选择难题。为工程设计中速饱和阻尼器阻尼电阻值的选择提供了新思路,对于CVT设计具有重要指导意义。
[Abstract]:Capacitive voltage transformer (Capacitor Voltage Transformer,CVT (capacitive voltage transformer) is an important electrical equipment in 110kV and above voltage grade of power system. Because CVT is mainly composed of capacitance and non-linear inductor, it is easy to excite its own harmonic ferroresonance under transient condition. At present, the main method to restrain CVT ferroresonance is to install dampers on the secondary side of CVT. Due to the excellent performance and damping characteristic of velocity saturation damper, it is widely used in CVT dampers. The value of damper resistance plays an important role in the damping effect of damper. However, there is little research on the selection of resistance values of velocity saturated dampers, and only a large upper limit range of damping resistance can be calculated by some formulas. In addition, because the calculation model is simple, the results often deviate greatly from the actual engineering situation. Therefore, in engineering, generally through a large number of ferroresonance tests to finally determine the optimal damping resistance required for CVT, this method has a large workload, resulting in a great waste of manpower and material resources. In addition, the research of CVT ferroresonance simulation model based on electromagnetic transient calculation software ATP-EMTP improves the accuracy of damping resistance selection, but the calculation is very large, and the accurate parameters of each element are needed. Based on the ferroresonance phenomenon and circuit oscillation conditions, the optimal calculation model of damping resistance selection for CVT velocity saturation dampers is established in this paper. According to the equivalent circuit of CVT, the loop equation of CVT equivalent circuit is established at first, and then the partial differential equation of one-dimensional cubic constant coefficient must be satisfied by using this equation to derive the damping resistance reaching damping condition. By solving the mathematical equation, the damping condition of CVT ferroresonance is obtained. According to this condition, the range of damping resistance can be calculated easily, and the value of damping resistance can be limited to a very small range. The calculation model is used to calculate the damping resistance of two CVT products in Wuxi-Japan New Factory of Jiangsu Province. It is found that the damping resistance calculated by the model is very close to the engineering selection resistance. The correctness and feasibility of the calculation model are proved. The calculation of this method is small and it can be used to guide engineering design. In order to fully demonstrate the correctness of the optimization model, the methods of modeling, simulation and field experiment are used to verify the range of damping resistance calculated by the optimal model of the CVT velocity saturation damper in this paper. In the aspect of software simulation, the CVT simulation model is established by using EMTP-ATP software, and the range of damping resistance determined by the calculation model is simulated by ferroresonance. In the field of experimental verification, several damping resistance values in the range determined by the computational model are selected to carry out ferroresonance experiments respectively. The results of simulation and experiment show that the model can effectively dampen ferroresonance, and it is proved that the model can solve the difficult problem of choosing damping resistance of CVT dampers. A new idea is provided for the selection of damping resistance of velocity saturated dampers in engineering design, and it is of great significance to the design of CVT.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM451

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