风电场经MMC-HVDC送出系统宽频带振荡机理与分析方法

Broadband Oscillation Mechanism and Analysis for Wind Farm Integration Through MMC-HVDC System

MMC柔性直流输电(modularmulti-levelconverter based HVDC,MMC-HVDC)具备向弱电网/无源系统提供电压和频率支撑的能力,逐渐成为弱电网/海上风电送出的一种新方式。部分风电场经MMC-HVDC送出工程发生宽频带振荡事故,振荡机理及分析方法亟待研究。建立直驱风电机组(permanent magnet synchronous generator,PSMG)/双馈风电机组(double fed induction generator,DFIG)阻抗与控制器参数间的数学模型,分析关键控制参数对风电机组宽频带阻抗特性的影响;建立MMC-HVDC序阻抗解析模型,分析其宽频带阻抗特性;基于最大峰值奈奎斯特稳定判据,分析系统振荡的边界条件,揭示直驱/双馈风电场经MMCHVDC送出系统发生宽频带振荡的机理;基于控制硬件在环仿真平台(control hardware in the loop,CHIL)时域仿真和阻抗扫描频域分析,验证振荡机理与分析方法的准确性。

Due to the ability of stabilizing voltage and frequency for weak/passive system,modular multi-level converter based HVDC(MMC-HVDC)has becoming a feasible approach for weak grid/offshore wind power delivery.Broadband oscillations were reported in certain number of MMC-HVDC projects with wind power,the mechanism and analytical method are urgent issues for studying.This paper established mathematical model between the sequence impedance of permanent magnet synchronous generator(PSMG)/double fed induction generator(DFIG)and their controller parameters,the influence of parameters on the sequence impedance characteristics were also studied.Sequence impedance model for MMC-HVDC was established,its broadband impedance characteristic was analyzed as well;Boundary condition of oscillation was proposed by maximumpeak-criteria-based Nyquist stability criterion,which was used to reveal broadband oscillation mechanism for wind farm integration through MMC-HVDC.Based on time-domain simulation based on control hardware in the loop(CHIL)simulation platform and frequency domain scanning of impedance,the oscillation mechanism and its analytical method are validated.