控制合闸电压幅值的变压器励磁涌流抑制方案

在分析变压器励磁涌流的影响因素和推导励磁涌流与各影响因素间数学关系的基础上,提出了一种基于合闸电压幅值控制的变压器励磁涌流抑制方案。该方案通过选择适当的合闸电压幅值控制曲线,对合闸电压的幅值进行控制,确保变压器空载合闸过程中产生的磁通不超过饱和磁通,从而达到抑制空载合闸励磁涌流的目的。根据磁通不等式约束与暂态磁通分量衰减规律给出了电压幅值控制函数,并推导了电压幅值控制函数中初值与变化斜率两个参数的上下限。采用PSCAD/EMTDC软件分别对单相和三相变压器不同状态下的空载合闸过程进行了仿真,并对磁通、励磁涌流、差动电流等参数进行了对比分析。仿真结果表明,通过控制合闸电压的幅值达到控制励磁电流大小的目的,能够将励磁涌流控制在数值较小的范围内,从而克服励磁涌流的影响。

Transformer Inrush Current Restraining Scheme Based on Switching Voltage Amplitude Controlling Method

A scheme of restraining transformer inrush current based on control by switching voltage amplitude is proposed based on analyzing the influencing factors of transformer inrush current and deriving the mathematical relationship between inrush current and influencing factors. In this scheme, in order to make sure that the magnetic flux produced by the transformer no-load closing does not exceed saturated magnetic flux, the voltage amplitude should be controlled by selecting an appropriate curve, thus attaining the goal of restraining the transformer inrush current. The control function of voltage amplitude is derived from the magnetic flux inequality and the attenuation law of the transient flux component, and the upper and lower limitations of the initial value and slope in the voltage amplitude control function are deduced. The no-load closing process of a single-phase and three-phase transformer each in different conditions is simulated by using PSCAD/EMTDC, and the parameters such as magnetic flux, excitation inrush current and differential current are analyzed. The simulation results show that by controlling the voltage amplitude, the inrush currents can be restrained. Using this scheme, the value of inrush current can be kept in a small range to better overcome the influence of transformer inrush current. This work is supported by National Natural Science Foundation of China(No. 51377100)and Shandong Provincial Natural Science Foundation of China(No. ZR2013EEM029).