控制系统扰动下并网变流器广义阻抗测量方法

Generalized-impedance Measurement for Grid-connected Converters Based on Perturbation in Control System

基于广义阻抗的频域分析方法可以将变流器并网系统的振荡问题转化为原–对偶电路中广义阻抗之间的串并联谐振问题。基于原–对偶电路,增加外界激励实现广义阻抗的测量具有可行性。为此,该文提出一种在控制系统注入扰动的广义阻抗测量方法。首先,针对主动注入扰动后的变流器系统建立其等效原–对偶电路,并分析系统在主动注入扰动后的响应;其次,给出在控制系统注入扰动的广义阻抗测量原理和计算方法;最后,比较了控制系统注入扰动与一次高压侧注入扰动以及理论值的测量误差。研究表明,在控制器的带宽范围内,在控制系统注入扰动的测量方法不仅可以有效测量出变流器的广义阻抗值,而且具有一次高压侧注入扰动的测量精度。

The frequency-domain analysis based on generalized-impedance transforms the oscillation analysis of grid-connected converter system into the resonance between the generalized-impedances of primal-dual circuit. Based on primal-dual circuit, it is feasible to measure the generalized- impedance through external excitation. A generalized- impedance measurement method based on perturbation in the control system was proposed in this paper. Firstly, an equivalent primal-dual circuit was established with injecting perturbation into the system, then the response of the system after injecting perturbation was analyzed. Secondly, the theory and method of measurement for generalized-impedance was put forward based on perturbation in control system. Finally, the measurement error of this method was compared with theoretical reference and measurement base on perturbation in primary side. It was proved that the proposed method based on perturbation in control system can effectively measure the converter generalized-impedance within control bandwidth.