基于CT的交流电源及其控制策略研究

针对目前高压线路在线监测装置供电难的问题,文中基于电流互感器的电流-电压变换原理建立了一种可为变负载供电的交流电源模型。采用一个三绕组电流互感器,通过电力电子设备来控制第三辅助绕组的状态。当辅助绕组短路时,铁芯饱和使得负载绕组输出电压为零;当辅助绕组开路时,负载绕组输出电压恢复,从而对负载绕组输出电压起到幅值调制的作用。设计了稳压反馈控制电路与基于多项式最小二乘曲线拟合函数法的稳压控制器算法,解决了在一次侧电流和所带负荷发生变化时,输出电压不稳定的问题,使负载及电流在一定范围内变化时输出电压能保持稳定。通过MATLAB/Simulink仿真平台验证了在可变负载情况下,所提出的基于CT交流电源有着良好的稳态和暂态输出特性,并对一次侧线路产生的影响可忽略不计。

Research on AC Power Supply Based on CT and Its Control Strategy

For the power supply problem of monitoring devices on long distance high-voltage transmission lines, this paper constructs an implementation framework of AC power source based on the current transformer (CT). First, the current transformer adding the third auxiliary winding is adopted in framework, and the power electronic circuit and a new control algorithm are used to control the state change of the third auxiliary winding, that is, when the auxiliary winding is shorted, the CT load winding voltage is zero, while the auxiliary winding is open, the CT load winding voltage output is recovered, so this control strategy modulates the amplitude of the designed power source output voltage. Then, a controller was designed for stabilizing power source output voltage and a new control algorithm considered the excitation nonlinearity of CT was proposed based on the least-squares curve fitting method. Finally, based on the simulation model established with Matlab/Simulink, the feasibility of designed AC power supply was validated with stable voltage output capability in the steady and transient operation, meanwhile the paper also verified that the designed power source influence on a primary current in the transmission line can be ignored.